Arbitration of Corruption Issues in Latin American Disputes
Corruption is an issue of increasing importance in arbitrations and post-award proceedings, particularly in Latin America, where there has been a surge of corruption-related investigations and charges in recent years, including the highly-publicised Lavo Jato probe in Brazil, and other similar investigations of public and private wrongdoing in jurisdictions such as Venezuela, Peru, Argentina, and Colombia. Indeed, according to Transparency International’s Corruption Perceptions Index 2021, on a scale from zero (highly corrupt) to 100 (very clean), approximately two-thirds of the countries assessed in the Americas scored below a 50, with an average score of 43, where ‘even high performers . . . show[ed] signs of trouble’. The consequences of corruption are felt in the public administration and private international community alike, and have led to a proliferation of recent arbitration cases – both commercial and investor-state – in which corruption-related claims play an important role in resolving the parties’ dispute. The arbitration community has mobilised to meet the new challenges caused by the increase in corruption-related allegations and cases worldwide, as evidenced by the International Chamber of Commerce (ICC)’s formation of a Task Force ‘Addressing Issues of Corruption in International Arbitration’ in order to explore existing and possible future approaches to dealing with allegations or indicia of corruption in arbitrations. While the ICC Task Force’s report and guidelines for tribunals is forthcoming, this chapter explores these very issues and attempts to investigate past practices, ongoing trends and areas of potential future development.
Allegations of corruption may impact arbitration proceedings at different stages, and in different respects. As described in greater detail throughout this chapter, (1) allegations of corruption may arise during an arbitration proceeding, in which a party may ask the arbitral tribunal or the tribunal may investigate sua sponte, possible acts of corruption; or (2) once the arbitration has concluded and an award has been issued, courts may be confronted with how allegations of corruption (and the arbitral tribunal’s consideration – or lack thereof – of such claims) impact whether the award should be recognised and enforced, or vacated.
As discussed in ‘Addressing corruption during an arbitral proceeding’, allegations or indicia of corruption in ongoing arbitration proceedings raise complicated questions for the arbitral tribunal as to whether they have the jurisdiction or duty to investigate such issues only at a party’s request, or should consider these issues sua sponte. A tribunal’s decision to delve into corruption considerations can give rise to a number of additional complex concerns, including as to the standard and burden of proof that should be applied. We also address when courts may consider allegations of corruption in post-award enforcement proceedings. Using the developing body of case law from US courts that have been called on to consider awards from Latin American jurisdictions or involving parties from Latin America, this section considers the extent to which national courts are likely to defer to any findings of fact or law made by a tribunal, in light of the strong public policy against corruption.
In general, this chapter reveals that, while there have been important recent developments in how tribunals and courts alike confront issues of corruption in arbitration, the law is far from settled. There exist important, and sometimes dispositive, differences not only across different jurisdictions where legal traditions may vary, but from tribunal to tribunal, court to court and case to case.
Addressing corruption during an arbitral proceeding
Cases involving corruption generally can be divided into two broad categories. The first category of cases – which are sometimes referred to as ‘easy’ (though they are by no means all ‘easy’ to deal with) – arise when a party expressly pleads corruption-related claims and requests relief in connection therewith. In such cases, the tribunal is generally thought to possess an obligation to decide the corruption issue, since it has the ‘duty to consider and resolve public policy (and other mandatory legal) objections’ presented by the parties. The second – and procedurally harder – category of cases involves indicia of corruption potentially affecting a claim or allegation put forward by a party but no express request by either party to address the corruption issue. This second set of cases pose especially complex questions for arbitrators and counsel. This section focuses on these ‘harder’ corruption cases. In particular, the following paragraphs discuss arbitrators’ duty to investigate corruption; the standard and burden of proof that applies; and the effect of parallel domestic proceedings on an ongoing arbitration.
Arbitral tribunals’ duty to investigate corruption
There is divergent jurisprudence and doctrine concerning the question whether arbitral tribunals have a duty to investigate or address indicia of corruption that may affect the parties’ claims. Some tribunals constituted under the aegis of the ICC have held that arbitrators are only under a duty to decide corruption-related issues in the event that one or more parties expressly requests that the arbitrators do so. These tribunals generally have reasoned that a tribunal’s duty to adjudicate an issue ordinarily arises only where the parties have requested that the tribunal resolve the issue. Other tribunals and commentators have queried whether the appearance of especially grave suspicions or facts – such as indicia of corruption – may call for a different interpretation of the scope of arbitrators’ duties.
In this vein, the UK High Court held in the Minmetals Germany GmbH case that, as long as the parties’ basic procedural rights are respected, then tribunals can, on their own initiative, investigate corruption. In reaching this conclusion, the UK High Court made clear that due process requires that the parties be afforded an opportunity to review and address any proposed findings by the tribunal on the matter of corruption. Other arbitral awards – and relevantly some involving Latin American countries – have gone further, finding that arbitral tribunals are not only allowed to investigate corruption on their own initiative, but that they could be under an obligation to do so. In Glencore v. Colombia, where Glencore claimed that Colombia had breached the fair and equitable treatment and non-impairment standards, as well as the umbrella clause of the bilateral investment treaty between Colombia and Switzerland, the tribunal was confronted with facts suggesting malfeasance. In deciding how to approach these facts, the tribunal concluded that ‘provided that there are prima facie grounds for suspecting malfeasance, an international arbitration tribunal has the duty to investigate the facts, even sua sponte, and to take appropriate measures under the applicable principles of law’.
The Glencore tribunal is not alone in taking this position. The award in Metal-Tech v. Uzbekistan reached the same conclusion.  Moreover, certain prominent commentators favour this approach, reasoning that arbitrators’ duty to investigate corruption stems from the public policy implications of corruption, which must take precedence over the parties’ decision to elide corruption issues in their submissions to tribunals.
To be sure, risks exist in adopting either approach. And in both cases these risks relate to the validity of the arbitral award. While awards have been set aside for arbitrators’ ultra petita decisions following sua sponte orders, arbitrators’ failure to investigate potential corruption issues might also result in annulment on public policy grounds. Arbitrators will have to balance these perils when deciding how to address indicia of corruption; and counsel should also consider the risks involved in requesting that tribunals address corruption issues or opposing tribunals’ sua sponte consideration of such issues.
Much like fraud and other similar acts, corruption is often difficult to prove. Accordingly, the standard and burden of proof that tribunals adopt in assessing corruption allegations may be outcome dispositive. It is therefore particularly important that parties pay due heed to the question of which law governs the standard and burden of proving corruption. There is conflicting case law in this regard. On the one hand, some arbitral tribunals have looked to the lex arbitri to answer such questions on the grounds that they are evidentiary issues. On the other hand, some tribunals apply the substantive governing law to questions relating to the standard and burden of proof for corruption allegations. And still other tribunals have opted to rely on international law standards to supply the rules regarding the standard and burden of proof for corruption allegations. To date, there is no predominant view on the matter, internationally or in Latin America, and the question therefore remains open and subject to debate. Arguably, it is preferable for tribunals to have the flexibility to decide on a case-by-case basis what the governing law must be, given the differing rules that may apply in different jurisdictions and the many forms that corruption may take.
Depending on the governing law, differing standards of proof may apply to allegations of corruption. For instance, in Dadras v. Iran, the arbitral tribunal concluded that allegations of forgery required ‘the application of a standard of proof greater than the customary civil standard of “preponderance of the evidence” ’. Likewise, some ICC tribunals have applied a more stringent standard of proof to allegations of fraud or corruption. In Latin America, the Glencore arbitration is potentially instructive. There, the tribunal concluded that there was no reason to elevate the standard of proof from the ordinary preponderance of the evidence standard, which was otherwise applicable under both the relevant treaty and the arbitral rules.
Again, depending on the applicable governing law, the burden of proof may also be an open question. The leading jurisprudence and doctrine recognise the general rule in international arbitrations that the party who alleges a fact has the burden of proving it (actori incumbit probatio). There have been some calls, though, for shifting or reversing the burden of proof in corruption cases. The Glencore case is again a leading Latin American arbitration on the matter. There, the tribunal found no reason to depart from the actori incumbit probatio principle. Instead, the tribunal followed the Spentex award, which found that ‘shifting the burden of proof and demanding evidence from the accused party that it did not engage in corrupt acts would subject such party to a probatio diabolica’. Certain prominent arbitrators, such as Alexis Mourre, as well as others, share this same view. Other tribunals have considered reversing the burden of proof when the party allegedly involved in the scheme is capable of adducing evidence without incurring an undue burden. And still other authors favour an ad hoc approach for these cases, under the premise that the only appropriate standard would be one based on the ‘inner conviction’ of the panel, even while acknowledging the ambiguity of such a standard.
A pair of arbitrations against the Uzbek state may also provide some guidance regarding evidentiary standards and approaches for dealing with corruption. First, the Spentex award followed a ‘connecting the dots’ approach, evaluating each of the individual indicia of corruption in detail and assessing the plausibility of an inference of corruption based on stringing the dots together. The tribunal ultimately ‘connected the dots’ to find that the investor and Uzbek state officials had engaged in corruption. Second, in the Metal-Tech Ltd case, the tribunal used internationally accepted ‘red flags’ and concluded that corruption occurred.
Effect of domestic procedures in an arbitration
It is not only conceivable but probable that arbitral proceedings relating to corruption will run in parallel to domestic court proceedings addressing closely connected facts; or that arbitral proceedings will follow on the heels of domestic court decisions on the matter. There is some recent Latin American jurisprudence addressing these parallel proceedings.
In the Vantage award, which related to the Lavo Jato probe in Brazil, the claimant alleged that Petrobras wrongfully terminated an offshore drilling rig lease agreement and requested damages for lost profits in connection therewith. The primary issue in the arbitration was whether the lease agreement had been procured through bribery and corruption. The arbitral tribunal issued an award in Vantage’s favour, holding that even if there had been corruption in the procurement of the lease agreement, Petrobras had ratified the agreement after becoming aware of the bribery allegations. In so holding, the tribunal rejected Petrobras’ claim that a Brazilian Federal Court judgment constituted conclusive evidence of the claimant’s participation in acts of bribery.
The Concesionaria Ruta Del Sol award, also connected to Lavo Jato, adopted a different view. There, the arbitral tribunal constituted under the aegis of the Bogotá Centre of Arbitration and Conciliation of the Chamber of Commerce, afforded substantial evidentiary weight to the parallel proceedings relating to the same underlying corruption.
The Glencore case, also a dispute involving Latin America, arguably lands in the middle of the other two precedents. On the one hand, the Glencore tribunal found that the pendency of criminal proceedings in Colombia was not automatically probative of corruption:
The Criminal Complaint and this procedure operate in different legal spheres, are subject to diverging standards of proof, and may reach conflicting results. The fact that the Colombian criminal system has not punished (in fact, in accordance with the available record, has not even investigated) the alleged corrupt practices surrounding the Eighth Amendment, does not preclude a hypothetical finding by this Tribunal that corruption has occurred. And vice-versa.
On the other hand, the tribunal recognised that it had to consider the findings by the Colombian criminal system in evaluating the available evidence. The Glencore award sets an interesting precedent because it recognises that arbitral tribunals may be reluctant to find that corruption occurred based solely on an ongoing parallel criminal proceeding, or on judgments issues by domestic courts; but it acknowledges that such decisions could have persuasive value.
Corruption as grounds for denying the enforcement of arbitral awards
Corruption concerns at times play an important role in the post-award phase. Enforcement regimes in the Americas and around the world generally recognise that corruption may provide a basis for vacatur of an arbitral award or for refusal to recognise or enforce the award. In this regard, it is essential to distinguish between two disparate types of corruption that may play a role in the post-award judicial proceedings: (1) corruption in the procurement of the contract or investment underlying the arbitral award (which may or may not afford a basis to refuse recognition and enforcement); and (2) corruption in the arbitral proceeding itself (which typically provides a basis for the vacatur, or set-aside, of an arbitration award at the place of the seat).
Below, we analyse recent corruption-related cases in which US courts were called upon to scrutinise arbitral awards involving Latin American parties or allegations of corruption that occurred in Latin America.
Corruption procuring the underlying contract
The most common instance of corruption considerations in the post-award phase of an arbitral proceeding, particularly in the commercial arbitration context, occurs when a party seeks to avoid enforcement of an arbitral award by contending that the award contravenes public policy, because the contract or investment that gave rise to the arbitration was procured by corruption (typically, through bribery or extortion). The New York Convention, which has been signed by 169 Member States as of the date of this publication, generally provides under its Article V(2)(b) that a court may exercise its discretion and refuse enforcement where ‘[t]he recognition or enforcement of the award would be contrary to the public policy of that country’. Article V(2)(b) is considered ‘[o]ne of the most frequently-asserted bases for refusing to recognize a foreign or non-domestic award’ and has been used in corruption-related cases.
The same provision is included in other legal instruments relevant to Latin America. The Panama Convention, a multilateral agreement that regulates the recognition and enforcement of arbitral awards where both parties hail from any one of the 19 countries in the Americas that have ratified the Convention to date, provides the same grounds for refusing enforcement as in the New York Convention. Moreover, the UNCITRAL Model Law on International Commercial Arbitration (UNCITRAL Model Law), which provides states with model text for modernising their laws on arbitration procedure, also lists public policy as a ground for non-recognition and enforcement. Because many jurisdictions in Latin America have implemented the UNCITRAL Model Law (or some variation thereof) in their domestic arbitration laws, those laws often contain a version of the public policy exception as well. This is the case, for instance, in Argentina, Chile, Colombia, Mexico and Peru.
Despite this large-scale codification of a public policy exception to the enforcement of arbitral awards, and a general international consensus that corruption is contrary to public policy, how courts apply this public policy exception varies from jurisdiction to jurisdiction. A key question in this respect is the extent to which it may re-examine a tribunal’s findings. The applicable standard of review differs by jurisdiction, and can range from minimalist, where the reviewing court accords significant deference to a tribunal’s factual and legal findings, to maximalist, where the court reviews the tribunal’s findings de novo.
In the United States, the debate about the appropriate standard of review in corruption-related cases is shaped by the tension between two fundamental policies. On the one hand, US courts favour limited judicial oversight of awards in order to advance the important pro-arbitration policy embodied in the Federal Arbitration Act (FAA) and avoid relitigation of issues presented to the arbitral panel. On the other hand, US courts are standard-bearers of US public policy, and have an interest in ensuring that arbitral awards involving allegations of corruption in the underlying contract may contravene fundamental values, undermine fair competition, and weaken the integrity of public administration. In applying these competing policies, US courts typically construe the grounds for resisting the enforcement of an award ‘narrowly’, afford substantial deference to arbitral tribunals’ findings of law and fact, and do not permit ‘re-litigat[ion]’ or reconsideration of the merits of any argument made before the tribunal. However, US courts may be more amenable to a thorough review if the arbitral tribunal fails to consider adequately the corruption issue.
Recent decisions in a case stemming from the Lavo Jato probe in Brazil, Vantage Deepwater Co v. Petrobras Am, Inc, demonstrate how US courts have interpreted judicial review of an arbitral award to be ‘extraordinarily narrow’ and ‘exceedingly deferential’ – despite ‘the [US’s] strong public policy against corruption abroad’. In Vantage, the Fifth Circuit explicitly rejected Petrobras’ argument that the court should consider the arbitrator’s legal findings de novo, while reviewing the arbitrator’s findings of fact only for clear error, and instead concluded that both a tribunal’s factual findings and its legal conclusions are entitled to deference. The Fifth Circuit distinguished between the review of the underlying contract and the final award, finding that the public policy exception under the New York Convention could apply if the award itself was the product of corruption, but that a claim of corruption in the underlying contract, as a substantive question of the enforceability and validity of a contract, ‘was a matter to be determined exclusively by the arbitrators’. Notably, the court held that the arbitrators’ consideration of whether corruption had been used to procure the underlying contract was entitled to deference ‘even if the arbitrators had made an error of law or fact’ in, for instance, deciding not to consider evidence of corruption.
Indeed, during the pendency of the arbitral proceedings in the Vantage case, the tribunal avoided the question of whether Vantage had, in fact, engaged in bribery; instead, it found that Petrobras had ‘ratified’ the contract after it had become aware of bribery allegations by continuing to accept the benefits thereunder, making the contract no longer voidable by Petrobras. In so doing, the tribunal rejected Petrobras’s argument that the contract was void and unenforceable because it had been procured through the bribery of foreign public officials. In the US enforcement proceedings, the US District Court of the Southern District of Texas declined to revisit the tribunal’s conclusions that ratification could cure a contract procured through bribery and that such ratification could occur even when a party was only aware of allegations of bribery.
Unsurprisingly, then, although parties ‘frequently raise’ Article V(2)(b) of the New York Convention and public policy concerns as grounds for trying to avoid enforcement of an award based on a contract procured through corruption, that defence against enforcement ‘has rarely been successful’. Specifically, where the arbitral panel considered the issue of corruption, but ‘did not find any corruption’ procuring the underlying contract, US courts are very unlikely to even consider whether the tribunal erred and corruption was present. As demonstrated by the District Court for the Southern District Court of New York’s decision in Commodities & Mins Enter, Ltd v. CVG Ferrominera Orinoco, CA, courts often consider that the enforceability of a contract allegedly procured by bribery is ‘a matter to be determined exclusively by the arbitrators’.
To the extent other US courts follow the Vantage and CVG Ferrominera cases, a party’s ability to avoid enforcement of an arbitral award on the basis that the underlying contract was the product of corruption, practically speaking, may be extremely limited in US courts. Parties suspecting that corruption played a role in obtaining the contract at issue will need to consider whether they wish to raise such allegations during the pendency of an arbitral proceeding. On the one hand, raising these allegations risks an adverse ruling by the tribunal (finding no corruption, for example), which is then likely to be accepted as a final determination that cannot be disturbed by a US court. On the other hand, failing to raise the issue before the tribunal where it could have been raised is likely to be viewed as a form of gamesmanship and will not necessarily preserve the issue for the court’s consideration. Consequently, on balance, it may be preferable for a party to raise such allegations of corruption during the arbitration, to avoid a later finding that such arguments were forfeited. It goes without saying that, where a party was unaware of possible corruption and its impact on the underlying contract, the arbitral proceeding, or the award until after the award was issued, that party may have a better argument and there may be a greater likelihood that the court will consider the issue.
Corruption in the arbitration proceeding itself
Corruption may also taint the arbitration procedure itself. There is an international consensus that corruption on the part of a tribunal member is a violation of the arbitral process. This type of arbitrator corruption can take many forms; in the most extreme examples, it takes the form of arbitrator or arbitrators accused of accepting bribes by a party to make a particular finding in the arbitration – this (admittedly rare) form of arbitrator corruption was alleged following an ICSID arbitration between the Peruvian government and Brazilian construction company Odebrecht in connection with the above-mentioned Lavo Jato probe, which culminated in the temporary detention of the tribunal members who were being investigated for accepting bribes. What is more common is ‘influence peddling’, where arbitrators are accused of bias or partiality through allegedly improper, undisclosed relationships with parties’ counsel or the appointed experts.
In instances of corruption in the arbitration proceeding itself, parties may have the choice to seek vacatur, or set-aside, of the arbitral award in the seat of arbitration, or can attempt to avoid enforcement of the award in other jurisdictions. The UNCITRAL Model Law provides that an arbitral award ‘may be set aside’ by a court if ‘the composition of the arbitral tribunal or the arbitral procedure was not in accordance with the agreement of the parties’, which also provides a basis on which a court can refuse enforcement. Similarly, in addition to the public policy exception in Article V(2)(b) of the New York Convention, Article V(1)(d) provides mandatory grounds for declining enforcement of arbitral awards where there are accusations of arbitrator partiality.
In conformity with these international model principles, countries have specifically enacted arbitration laws that reflect an aversion to arbitrator corruption. Specifically, the FAA – which, among other things, regulates the vacatur and enforcement of arbitral awards in the United States – expressly includes, as two of the four grounds for vacatur of an arbitral award, ‘where there was evident partiality or corruption in the arbitrators’ or ‘where the arbitrators were guilty of . . . any other misbehaviour by which the rights of any party have been prejudiced’. Article 32 of the Brazil Arbitration Act likewise enumerates the grounds on which arbitral awards may be set aside, and provides for nullification of an award that was procured by any one of three types of corruption crimes under Brazilian law (prevaricação, concussão, or corrupção passiva).
While parties have recourse against corruption in the arbitration process itself in the form of vacatur or the ability to avoid enforcement elsewhere, in practice, these are difficult allegations to raise, and there appear to be very few (if any) cases in which US courts were called on to consider in the post-award stage whether an arbitral process was itself tainted by arbitrator bribery. Such cases may involve facts that are only discovered or come to light in the post-arbitration stage, as it could be difficult to uncover evidence of corruption during the arbitration. In such instances, US courts may be more willing to consider these cases applying a de novo standard of review, accessing the facts and law anew without any deference to the underlying arbitration proceeding (which itself is accused of being defective).
Indeed, US courts have drawn a distinction between the ability to consider the impact of corruption in the arbitral award, which courts have found can be a basis to decline enforcement of an award, and the impact of corruption in the underlying contract that was at issue in the arbitration, which might not be. This is consistent with Chapter 1 of the FAA, which enumerates as one ground for vacatur ‘where the award was procured by corruption, fraud, or undue means’. To meet this threshold, some courts have held that the petitioner must establish corruption, fraud or undue means by clear and convincing evidence; demonstrate that the corruption, fraud or undue means was not discoverable upon the exercise of due diligence or during the arbitration; and prove that the fraud materially related to an issue in the arbitration. In the more-often litigated and less extreme examples of arbitrator bias or partiality, US courts generally look to the facts presented by the parties, but still remain reticent to disturb arbitral awards except in more egregious cases where there is a clear and direct financial benefit that the arbitrator stood to gain from the undisclosed relationship, although other jurisdictions may have different approaches.
While originally conceived as a private method of dispute resolution, today most arbitrators and the doctrine recognise that arbitration serves a public policy function. Under this conception, corruption, which naturally threatens or damages public policy, is a key topic. The most relevant and recent arbitral awards dealing with corruption – many of which touch upon Latin American jurisdictions – illustrate that corruption may call for special treatment both during and after an arbitral proceeding.
While the proceeding is ongoing, some jurisprudence and commentary holds that arbitrators possess an obligation to investigate, even sua sponte, indicia of corruption. Doing so, however, can result in the award’s annulment on the basis that the arbitrators have acted ultra petita. Yet, the opposite approach could produce an annulment on public policy grounds. Once a party raises corruption-related issues, questions of applicable law, and standard and burden of proof arise. Given the still scarce and diverging case law dealing with corruption, there is room for arbitrators and parties to innovate in this regard.
Once the arbitral award is issued, domestic courts may be confronted with whether to vacate or enforce the award on the basis of corruption. Where the efforts to resist enforcement depend on alleged corruption in the underlying contract or allegations of corruption in the arbitration process itself, courts’ approaches may differ. When the issue relates to contracts procured through corruption, US courts often give substantial deference to the tribunal’s findings of law and facts, even where the tribunal declined to consider certain allegations of corruption. Where the allegations are that the arbitral process itself was corrupted – through arbitrator bribery or less extreme instances of corruption, such as bias or partiality – US courts may be more willing to consider and investigate the allegations anew.
 Ari D MacKinnon is a partner in the New York Office of Cleary Gottlieb Steen & Hamilton LLP. This chapter was written with the contributions of Katie L Gonzalez, Elisa Zavala, and Roberta T Mayerle, associates at Cleary Gottlieb Steen & Hamilton LLP. The opinions expressed are those of the authors and do not necessarily reflect the views of Cleary Gottlieb Steen & Hamilton LLP, its clients, or any of its or their respective affiliates. This chapter is for general information purposes and is not intended to be and should not be taken as legal advice.
 Despite the prevalence of corruption-related allegations and claims in both commercial and investor-state arbitration proceedings, and the international community’s broad condemnation of corruption in all forms, corruption has no universal definition. Instead, the term ‘corruption’ is generally used as an umbrella term to denote a wide variety of offences, including, for example, bribery, abuse of power, embezzlement, extortion, misappropriation of property, or abuse of power or discretion. See, e.g., UN Convention Against Corruption, 31 October 2003, 2349 U.N.T.S. 41, chap. III.
 Transparency International, Corruption Perceptions Index 2021, at 12 (5 January 2022), https://images.transparencycdn.org/images/CPI2021_Report_EN-web.pdf.
 Gary B Born, Chapter 19: Choice of Substantive Law in International Arbitration, in International Commercial Arbitration 2706, 2915 (3d ed. 2021).
 Case No. 7047 of 1994, 21 Y.B. Comm. Arb. 79, 93 ¶ 54 (ICC Int’l Ct. Arb.) (The tribunal held that ‘The word “bribery” is clear and unmistakable. If the defendant does not use it in his presentation of facts an Arbitral Tribunal does not have to investigate. It is exclusively the parties’ presentation of facts that decides in what direction the arbitral tribunal has to investigate’.).
 See Minmetals Germany GmbH v. Ferco Steel Ltd.  1 All E.R. (Comm.) 315.
 See, e.g., Glencore Int’l A.G. et al. v. Republic of Colom., ICSID Case No. ARB/16/6, Award, ¶ 664 (22 September 2021).
 id. (citation omitted).
 Metal-Tech Ltd. v. Republic of Uzb., ICSID Case No. ARB/10/3, Award, ¶ 241 (4 October 2013) (noting the tribunal had a ‘duty to inquire’ the consulting payments and ordering further discovery on this issue).
 See Vladimir Khvalei, Chapter 4: Standards of Proof for Allegations of Corruption in International Arbitration, in 13 Addressing Issues of Corruption In Commercial and Investment Arbitration – Investment Arbitration – Institute Dossier XIII 69, 74 (Domitille Baizeau and Richard H Kreindler eds, 2015); Edoardo Marcenaro, Chapter 9: Arbitrators’ Investigative and Reporting Rights and Duties on Corruption, in 13 Addressing Issues of Corruption In Commercial and Investment Arbitration – Investment Arbitration – Institute Dossier XIII 141, 145 (Domitille Baizeau and Richard H Kreindler eds, 2015); Aloysius Llamzon, Corruption in International Investment Arbitration 228 (Oxford University Press, 2014).
 Marcenaro, supra note 12, at 145.
 Llamzon, supra note 12, at 230–32; Andrea Menaker, Chapter 5: Proving Corruption in International Arbitration, in 13 Addressing Issues of Corruption In Commercial and Investment Arbitration – Investment Arbitration – Institute Dossier XIII 77, 78 (Domitille Baizeau and Richard H Kreindler eds., 2015).
 Petrobart Ltd. v. Republic of Kyrg., UNCITRAL, Award, at 45 (13 February 2003). See Menaker, supra note 15, at 78.
 Oostergetel v. Slovak Republic, UNCITRAL, Award (redacted) ¶ 147 (23 April 2012); Metal-Tech, supra note 11, ¶ 238. See Menaker, supra note 15, at 78; Domitille Baizeau and Tessa Hayes, The Arbitral Tribunal’s Duty and Power to Address Corruption Sua Sponte in 19 International Arbitration and the Rule of Law: Contribution and Conformity, ICCA Congress Series 225, 232 (Andrea Menaker ed., 2017).
 World Duty Free Company Limited v. Republic of Kenya, ICSID Case No. ARB/00/7, ¶ 157 (4 October 2006) (noting that ‘[i]n light of domestic laws and international conventions relating to corruption, and in light of the decisions taken in this matter by courts and arbitral tribunals, this Tribunal is convinced that bribery is contrary to the international public policy of most, if not all, States or, to use another formula, to transnational public policy’.).
 The most popular approaches, following the common law approach to standards of proof, include a higher standard of proof, like those requiring ‘clear and convincing evidence’, ‘more likely than not’ or ‘beyond a reasonable doubt’; the usual standard in arbitration, which usually takes the form of ‘preponderance of the evidence’ or ‘balance of probabilities’; and some arbitral tribunals have followed a lower standard, such as when concluding that corruption existed on the basis of indirect or circumstantial evidence. Jurisdictions of civil law tradition do not distinguish between these same categories, and instead tend to have the same standard apply in both civil and criminal cases, or they sometimes only distinguish between two thresholds. Authors disagree on how civil law standards compare with common law ones. See Khvalei, supra note 12, at 69; see also Llamzon, supra note 12, at 232 (explaining that common law systems tend to apply a ‘balance of probabilities’ standard to civil cases, while civil ones typically adopt the ‘inner conviction’ standard; and further clarifying that international arbitration tends to follow the common law approach).
 Dadras Int’l v. Islamic Republic of Iran, 31 Iran-U.S. Cl. Trib. Rep. 135-36 (1995).
 See Westinghouse Int’l Projects Co. v. Nat’l Power Corp., Case No. 6401 of 1991, 7 Mealey’s Int’l Arb. Rep., § B, at B-1 (ICC Int’l Ct. Arb.) (concluding that ‘a higher standard of “clear and convincing evidence” would, however, apply: fraud in civil (as compared to criminal) cases must be proven to exist by clear and convincing evidence amounting to more than a mere preponderance, and cannot be justified by mere speculation’.).
 Glencore Int’l, supra note 8, ¶ 669 (‘As for the standard to be applied to assess the evidence, the Tribunal perceives no reason to depart from the traditional standard of preponderance of the evidence, since neither the Treaty nor the ICSID Arbitration Rules impose a different standard’.).
 See Glencore Int’l, supra note 8, ¶ 668; Metal-Tech, supra note 11, ¶ 297; Menaker, supra note 15, at 80 (citing Case No. 7047 of 1994, 21 Y.B. Comm. Arb. 79, 93 ¶ 53 (ICC Int’l Comm. Arb.); Case No. 13384 of 2005, 24 Int’l Ct. Arb. Bull. 62 (ICC Int’l Ct. Arb.)).
 See Glencore Int’l, supra note 8, ¶ 668.
 Glencore Int’l, supra note 8, ¶ 574 (citing Spentex Netherlands B.V. v. Republic of Uzb., ICSID Case No. ARB/13/26, Final Award, (27 December 2016) (non-public)).
 Khvalei, supra note 12, at 81 (citing Alexis Mourre, Arbitration and Criminal Law: Reflections on the Duties of the Arbitrator, 22 Arb. Int’l 95, 103 (2006)).
 id. at 81 (citing Vecchi v. Arab Republic of Egypt, ICSID Case No. ARB/05/15, Award, ¶¶ 316–17 (1 June 2009)).
 Case No. 6497 of 1994, 24 Y.B. Comm. Arb. 71, 73 ¶ 3–4 (ICC Int’l Comm. Arb.) (remarking that ‘[t]he “alleging Party” has the burden of proof . . . [such party] may bring some relevant evidence for its allegations, without these elements being really conclusive. In such case, the arbitral tribunal may exceptionally request the other party to bring some counterevidence, if such task is possible and not too burdensome. If the other party does not bring such counter-evidence, the arbitral tribunal may conclude that the facts alleged are proven. . . . However, such change in the burden of proof is only to be made in special circumstances and for very good reasons’.).
 See Khvalei, supra note 12, at 74.
 Glencore Int’l, supra note 8, ¶ 574 (citing Spentex Netherlands B.V. v. Republic of Uzb., ICSID Case No. ARB/13/26, Final Award, (27 December 2016) (non-public)).
 Metal-Tech, supra note 11, ¶ 293.
 Vantage Deepwater Co. v. Petrobras America Inc., ICDR Case No. 01-15-0004-8503 of 2018, ¶¶ 23–27 (29 June 2018).
 id. ¶¶ 276, 286–91.
 id. ¶¶ 276, 286–92.
 Tribunal Arbitral De Concesionaria Ruta del Sol S.A.S. v. Agencia Nacional de Infraestructura, CCB Case Nos. 4190 & 4209 of 2019, at 392–402 (identifying as evidence of corruption the complaint and lawsuit filed by the US Department of Justice against Odebrecht before a New York state court and the plea agreement between the US Department of Justice and Odebrecht before a New York state court).
 Glencore Int’l, supra note 8, ¶ 673 (‘The Criminal Complaint and this procedure operate in different legal spheres, are subject to diverging standards of proof, and may reach conflicting results. The fact that the Colombian criminal system has not punished (in fact, in accordance with the available record, has not even investigated) the alleged corrupt practices surrounding the Eighth Amendment, does not preclude a hypothetical finding by this Tribunal that corruption has occurred. And vice-versa’.).
 id. ¶ 674.
 Given the general public policy in favour of arbitration in many jurisdictions around the globe, courts of these jurisdictions are loathe to intervene during pending arbitration proceedings, even if a party raises the possibility of corruption of the underlying contract. In the United States in particular, a majority of courts have read the Federal Arbitration Act (FAA) to expressly preclude any mid-arbitration intervention. See, e.g., Savers Prop. & Cas. Ins. Co. v. Nat’l Union Fire Ins. Co., 748 F.3d 708, 717-18 (6th Cir. 2014) (stating that the Courts of Appeal for the Second, Third, Fourth, Fifth, Sixth and Seventh, and DC Circuits do not permit an interlocutory review of arbitration proceedings and interim arbitral panel decisions by courts); see also In re Sussex, 781 F.3d 1065, 1073 (9th Cir. 2015) (noting that ‘[t]he majority of our sister circuits expressly preclude any mid-arbitration intervention’ and citing cases). While a minority of US courts, including the Court of Appeals for the Ninth Circuit, have permitted intervention, they have done so ‘only in the most extreme cases’, where ‘severe irreparable injury’ or ‘manifest injustice’ would occur if not for the court’s collateral review’. See In re Sussex, 781 F.3d at 1072-73, 1075. Consequently, courts’ review of arbitrations for any corruption-related concerns is likely limited to the post-award proceedings.
 Convention on the Recognition and Enforcement of Foreign Arbitral Awards, Art. V(2)(b), 10 June 1958, 330 U.N.T.S. 38 (NY Conv). Reviewing courts in different jurisdictions disagree on whose public policy is at issue – that of the seat of arbitration, that defined by the seat, or that of the place of attempted enforcement. US courts have focused on US public policy. See Belize Bank Ltd. v. Gov’t of Belize, 852 F.3d 1107, 1111 (D.C. Cir 2017).
 Born, supra note 4, at 4000.
 Inter-American Convention on International Commercial Arbitration, Art. 5, 20 January 1975, O.A.S.T.S. No. 42, 1438 U.N.T.S. 245. The Panama Convention has been signed and ratified by 19 countries to date, including the United States, Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Dominican Republic, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Uruguay and Venezuela.
 UNCITRAL Model Law, 1985 (amended in 2006) Art. 36(1)(b)(ii) (stating that ‘[r]ecognition or enforcement of an arbitral award, irrespective of the country in which it was made, may be refused . . . if the court finds that: . . . the recognition or enforcement of the award would be contrary to the public policy of this State’).
 UNCITRAL lists more than 10 Latin American countries that adopted legislation based on the UNCITRAL Model Law, including Argentina, Chile, Costa Rica, Dominican Republic, Guatemala, Honduras, Mexico, Nicaragua, Paraguay, Peru and Venezuela. See UNCITRAL, Status: UNCITRAL Model Law on International Commercial Arbitration (1985), with amendments as adopted in 2006, https://uncitral.un.org/en/texts/arbitration/modellaw/commercial_arbitration/status. Other Latin American countries have adopted the public policy exception as well, including Chile, Colombia and Peru. See Law No. 19.971, Art. 36, 29 September 2004, Diario Oficial [D.O.] (Chile); D.L. 1563, 2 June 2012, Diario Oficial [D.O.], Art. 112 (Colom.); D. L. 1071, Section 63, 1 September 2008, https://www.gob.pe/institucion/osce/normas-legales/308659-1071 (Peru). While Brazil’s Arbitration Act does not include a public policy exception, domestic courts in Brazil have recognised it as a ground for annulment of arbitral awards. See, e.g., Octavio Fragata Martins de Barros and Carlos Gustavo Rodrigues Reis, ‘The Setting Aside Of Arbitral Awards In Brazil: Some Recent Case Law And An Exception To The Restrictive List Provided Under The Brazilian Arbitration Act’, Who’s Who Legal (2 November 2021), https://whoswholegal.com/features/the-setting-aside-of-arbitral-awards-in-brazil-some-recent-case-law-and-an-exception-to-the-restrictive-list-provided-under-the-brazilian-arbitration-act.
 International Law Association, Interim Report on Public Policy as a Bar to Enforcement of International Arbitral Awards (2000); Richard H Kreindler, Concluding Remarks: Corruption and International Arbitration Is Anything Broken or Otherwise Worth Fixing?, in Addressing Issues of Corruption In Commercial and Investment Arbitration – Investment Arbitration – Institute Dossier XIII 187 (Domitille Baizeau and Richard H Kreindler eds, 2015).
 See, e.g., Michael Hwang SC and Kevin Lim, Corruption in Arbitration — Law and Reality, 8 Asian Int’l Arb. J. 1, 52–64 (2012).
 See Richard H Kreindler, Aspects of Illegality in the Formation and Performance of Contracts, in International Commercial Arbitration: Important Contemporary Questions 209, 218 (Albert Jan van den Berg ed., 2002) (quoting Westacre Inv. Inc. v. Jugoimport–SPDR Holding Co. Ltd.  QB 740 (Eng.).
 See Mitsubishi Motors Corp. v. Soler Chrysler-Plymouth, Inc., 473 U.S. 614, 629 (1985); Andes Petroleum Ecuador Ltd. v. Occidental Expl. & Prod. Co. Eyeglasses, 21 Civ. 3930 (AKH), 2021 WL 5303860, at *4 (S.D.N.Y. 15 November 2021), aff’d Guerrero v. Occidental Petroleum Corp., No. 20-20633, 2022 WL1421399 (5th Cir. May 5, 2022) (‘A court’s review of an arbitration award is “severely limited in view of the strong deference courts afford to the arbitral process”. This limitation prevents frustration of the “twin goals of arbitration, namely, settling disputes efficiently and avoiding long and expensive litigation”’. (citations omitted)).
 See Hwang and Lim, supra note 47, at 51.
 See, e.g., Vantage Deepwater Co. v. Petrobras America, Inc, Civil Action No. 4:18-CV-02246, 2019 WL 2161037, at *10 (S.D. Tex. 17 May 2019), aff’d, 966 F.3d 361 (5th Cir. 2020), cert. denied, 141 S. Ct. 1395 (2021). Note: the author and the firm represented Petrobras in this case.
 id. at *2 (internal quotation marks omitted).
 See, e.g., BCB Holdings Ltd. v. Gov’t of Belize, 232 F. Supp. 3d 28, 49 (D.D.C. 2017); Belize Soc. Dev. Ltd. v. Gov’t of Belize, 5 F. Supp. 3d 25, 43 (D.D.C. 2013), aff’d, 794 F.3d 99 (D.C. Cir. 2015).
 Vantage, 966 F.3d at 370–72; see also W.R. Grace & Co. v. Loc. Union 759, Int’l Union of United Rubber, Cork, Linoleum & Plastic Workers of Am., 461 U.S. 757, 766 (1983) (‘[T]he question of public policy is ultimately one for resolution by the courts’. (citation omitted)).
 Vantage, 966 F.3d at 368 (‘“A court may not review the merits of an [arbitration] award — it must accept the facts found by the arbitrator and the arbitrator’s interpretation of the contract and applicable law ”’. (quoting Manville Forest Prods. Corp. v. United Paperworkers Int’l Union, 831 F.2d 72, 74 (5th Cir. 1987))); see also id. at 372 (‘When we defer to that finding, the legal conclusion follows that the [agreement for the provision of drilling services], and the arbitration award, did not violate public policy’); Northrop Corp. v. Triad Int’l Mktg. S.A., 811 F.2d 1265, 1269 (9th Cir. 1987) (finding that the arbitrators’ conclusions on legal issues were entitled to deference because ‘[t]o now subject these decisions to de novo review would . . . render the exhaustive arbitration process merely a prelude to the judicial litigation which the parties sought to avoid’), amended, 842 F.2d 1154 (9th Cir. 1988).
 Vantage, 966 F.3d at 371 (quoting Europcar Italia, S.p.A. v. Maiellano Tours, Inc., 156 F.3d 310, 315 (2d. Cir. 1998)); see infra note 73.
 id. (quoting Europcar, 156 F.3d at 315–16).
 id. at *10.
 See Vantage, 2019 WL 2161037, at *10; Vantage, 966 F.3d at 372 (finding that ‘[w]hether a contract should be voided because of bribery is a question about the validity of the [contract],’ which was ‘rightly a question for the arbitrators rather than the district court’.). More alarmingly, the District Court found that because Petrobras senior executives had accepted the bribes in question, Petrobras had mutually engaged in misconduct during the formation of the contract and could not use that misconduct to avoid the contract. See Vantage, 2019 WL 2161037, at *11. The Circuit Court did not reject this reasoning, but highlighted that the District Court did not base its decision just on ‘mutual misconduct’. Vantage, 966 F.3d at 372. This ‘two-to-tango’ argument would substantially vitiate any bribery defence in the future and it accordingly remains to be seen whether courts will rely on this doctrine in the future.
 Ministry of Def. & Support for the Armed Forces of the Islamic Republic of Iran v. Cubic Def. Sys., Inc., 665 F.3d 1091, 1097 (9th Cir. 2011); see also BCB Holdings, 232 F. Supp. 3d at 49 (noting that the party resisting enforcement on corruption grounds ‘cannot point to any cases in which a court declined to enforce an arbitral award because it violated the United States’ public policy against government corruption’).
 BCB Holdings Ltd. v. Gov’t of Belize, 650 F. App’x 17, 19 (D.D.C. 2016).
 1:19-CV-11654-ALC, 2020 WL 7261111, at *6 (S.D.N.Y. 10 December 2020) (quoting Europcar Italia, S.p.A. v. Maiellano Tours, Inc., 156 F.3d 310, 315 (2d Cir. 1998)).
 See, e.g., AAOT Foreign Econ. Ass’n (VO) Technostroyexport v. Int’l Dev. & Trade Servs., Inc., 139 F.3d 980 (2d Cir. 1998) (finding, in context of alleged arbitrator corruption, that ‘[t]he settled law of this circuit precludes attacks on the qualifications of arbitrators on grounds previously known but not raised until after an award has been rendered.’).
 See Global Arbitration Review, ‘Arbitrators jailed in Peru amid Odebrecht corruption scandal’, (7 November 2019), https://globalarbitrationreview.com/article/arbitrators-jailed-in-peru-amid-odebrecht-corruption-scandal; Billy Franco and Kate Cervantes-Knox, ‘Arbitrators who were imprisoned in Peru have been released, but remain subject to significant restrictions on their freedom pending corruption investigations’ (5 December 2019), https://www.dlapiper.com/en/us/insights/publications/2019/12/arbitrators-imprisoned-in-peru/.
 Baizeau and Hayes, supra note 17.
 The IBA Guidelines on Conflicts of Interest in International Arbitration describe circumstances that may raise doubts as to the arbitrator’s impartiality, and provide ‘Red List,’ ‘Orange List,’ and ‘Green List’ activities that may pose varying degrees of concern if present. See IBA Guidelines on Conflict of Interest in International Arbitration, International Bar Association (23 October 2014), https://www.ibanet.org/MediaHandler?id=e2fe5e72-eb14-4bba-b10d-d33dafee8918; see, e.g., id. at 4 (‘(1) General Principle [—] Every arbitrator shall be impartial and independent of the parties at the time of accepting an appointment to serve and shall remain so until the final award has been rendered or the proceedings have otherwise finally terminated’).
 UNCITRAL Model Law, Arts. 34(2)(iv), 36(1)(a)(iv).
 NY Conv, Arts. V(1)(d), V(2)(b); see, e.g., Belize Bank, 852 F.3d at 1110-14 (applying Art. V(2)(b) in arbitrator impartiality case).
 9 U.S.C. § 10(a)(2)-(3).
 Lei No. 9.307, de 23 de Setembro de 1996, Diário Oficial da União, Art. 32 [D.O.U.] de 24.11.1996 (Braz.), https://www.jus.uio.no/lm/brazil.arbitration.law.no.9.307.1996/doc.html#138 (‘An arbitral is null and void if . . . it has been duly proved that it was made through unfaithfulness, extortion or corruption’).
 One case to watch on this topic is Metropolitan Municipality of Lima v. Rutas de Lima S.A.C., No. 1:20-cv-02155 (D.D.C. 23 December 2020), which is currently pending before the D.C. district court. In this case, the Metropolitan Municipality of Lima (MML) is seeking vacatur of an arbitral award pursuant to Section 10(a)(1) of the FAA, on the basis that Rutas de Lima S.A.C. (Rutas) fraudulently denied, throughout the arbitration proceeding, that the underlying concession contract was procured through corruption, thereby causing the tribunal to deny that the contract should be declared null and void and awarding Rutas approximately US$67 million in damages, and that ‘new evidence’ adduced after the final award was issued demonstrates that the contract was procured by a bribe. id., at 2, 20. The D.C. district court’s consideration of this issue, and the standard it will apply to review such allegations, remains to be seen.
 See Vantage, 1:19-CV-11654-ALC, 2020 WL 7261111, at *6 (public policy exception ‘applies only where enforcement of the arbitration award, as opposed to enforcement of the underlying contract’ is at issue); Vantage, 966 F.3d at 371 (‘[The defendant-appellant] has apparently confused the issue of a fraudulently obtained arbitration agreement or award, which might violate public policy and therefore preclude enforcement, with the issue of whether the underlying contract that is subject of the arbitrated dispute was forged or fraudulently induced – a matter to be determined exclusively by the arbitrators’. (quoting Europcar Italia, S.p.A. v. Maiellano Tours, Inc., 156 F.3d 310, 315 (2d Cir. 1998))).
 9 U.S.C. § 10(a)(1).
 See, e.g., RZS Holdings AVV v. PDVSA Petroleos S.A., 598 F. Supp. 2d 762, 771 (E.D. Va. 2009), aff’d sub nom. RZS Holdings AVV v. PDVSA Petroleo S.A., 383 F. App’x 281 (4th Cir. 2010); see also Nat’l Indem. Co. v. IRB Brasil Resseguros S.A., 164 F. Supp. 3d 457, 485 (S.D.N.Y. 2016), amended, No. 15 CIV. 1165 (NRB), 2016 WL 3144057 (S.D.N.Y. 14 April 2016), and aff’d sub nom. Nat’l Indem. Co. v. IRB Brasil Reseguros S.A., 675 F. App’x 89 (2d Cir. 2017), and enforcement granted, No. 15 CIV. 3975 (NRB), 2018 WL 739450 (S.D.N.Y. 23 January 2018), vacated on other grounds, 767 F. App’x 154 (2d Cir. 2019) (finding that failure by defendant’s counsel to disclose the arbitrator’s participation in another arbitration involving an entity related to the defendant did not constitute procurement of the awards by ‘undue means’); Luzar Trading, S.A. v. Tradiverse Corp., 20-CV-623 (KMW), 20-CV-3387 (KMW), 2021 WL 1164041, at *7 (S.D.N.Y. 25 March 2021) (finding that US$100,000 settlement payment made to an arbitrator on one of two panels was not grounds for vacatur because the defendant failed to provide evidence as to why the payment was fraudulent and as to how the payment was materially related to the issues before the panel that the arbitrator who received the payment was not on).
 See, e.g., Nat’l Indem. Co., 2016 WL 3144057, at *1; Andes Petroleum, 2021 WL 5303860, at *4.
 For example, in Ometto v. ASA Bioenergy Holding AG, New York federal Judge Jed S Rakoff denied a petition to vacate an arbitral award on the basis of alleged impartiality by an arbitrator whose firm had acted for the defendant Abengoa in a number of corporate transactions, finding that the conflict of interest was inadvertent. No. 12 CIV 1328 JSR, 2013 WL 174259 (S.D.N.Y. Jan. 9, 2013), aff’d, 549 F. App’x 41 (2d Cir. 2014). However, when Abengoa attempted to enforce the award in Brazil, the Superior Tribunal de Justiça, Brazil’s Superior Court, declined to enforce the award, finding – in contrast to the New York court – that the failure to disclose the conflict of interest violated Brazilian public policy. See María Eduarda Lemgruber, Recognition of Foreign Arbitral Awards in Brazil: The Abengoa Decision One Year On (3 May 2018), http://arbitrationblog.kluwerarbitration.com/2018/05/03/recognition-foreign-arbitral-awards-brazil-abengoa-decision-one-year/.