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November 10, 2020

International Extradition: A Guide to U.S. and International Practice



The U.S. government's efforts to extradite Julian Assange from the United Kingdom have prompted broad discussion of—and questions about—the law and practice of international extradition.1 A decision in the Assange case is expected early next year.2 Other recent well-publicized international extradition cases include those of Omar Ameen, an Iraqi refugee in the United States whom Iraq sought on what critics call a questionable murder charge.3 Mullah Krekar, an Iraqi Kurdish cleric extradited from Norway to Italy following his conviction in Italy for leading a jihadist group;4 and Emilio Lozoya, the former chief of the Mexican state oil firm Pemex, who was arrested in Spain earlier this year as Mexico prepared to seek his extradition on corruption charges.5

For each of these well-known cases handled by authorities around the world, however, U.S. diplomatic and law enforcement authorities deal with dozens of important but lower-profile requests for extradition—both to and from the United States—as part of the regular work of international law enforcement cooperation.

The process by which the United States evaluates these incoming and potential outgoing extradition requests may be unfamiliar to some practitioners. This Advisory is meant to provide a basic primer for those interested in understanding the law and practice of international extradition, with a focus on the U.S. process. It first addresses the basic elements common to most bilateral extradition treaties. Next, it describes the process for extradition to and from the United States. Finally, it discusses some of the defenses most commonly raised in extradition cases, along with suggestions for handling such matters to achieve the best results for individuals facing potential extradition.

General Overview of Extradition Treaties

Extradition treaties are intended to operate like contracts and obligate the parties to arrest and surrender a person to a foreign treaty partner upon request, provided that the treaty's requirements are met and no exceptions apply. Extradition treaties are individually negotiated and may vary in order to accommodate the legal systems and priorities of the negotiating countries, but they generally share common elements. They establish requirements for both the country sending the extradition request (the "requesting state") and the country receiving the request (the "requested state").

The United States has extradition treaties with more than 100 countries.6 U.S. extradition proceedings are also subject to the requirements of U.S. statutory law, most importantly those codified at 18 U.S.C. § 3181 et seq. In general, the United States will extradite an individual to another country only under the authority of a bilateral extradition treaty with that country,7 but it will accept fugitives from other countries whether based on a bilateral extradition treaty, the provisions of a multilateral convention,8 or other means of return.9

We discuss the elements common to most extradition treaties below.

Extraditable offenses. All treaties include provisions defining which crimes are extraditable. Treaties agreed upon prior to the 1970s typically contain a negotiated list of specific extraditable offenses (such as "murder," "manslaughter," or "larceny") and permit extradition only for the crimes that are listed in the treaty. Modern treaties have largely done away with these lists, however, and use a "dual criminality" approach instead.10 This more flexible approach examines the conduct that serves as the basis for the request.11

Exceptions to extradition. Every extradition treaty contains exceptions to the parties' extradition obligations. The most common exceptions include:

  • Political offenses. These provisions are aimed at crimes such as treason, espionage, and other offenses that could be used to target political opponents or otherwise cause the requested state to become entangled in the domestic politics of the requesting state. To clarify and limit the contours of the "political offense" exception, most U.S. bilateral treaties now exempt violent conduct such as bombings and hostage-taking from the exception, even if the individual sought for extradition asserts that the conduct in question was political in nature.12
  • Nationality. Many countries refuse to extradite their own nationals, and where that position prevails in negotiations, an extradition treaty may include an exception for this policy. The U.S. government has long held the view that nationality should not operate as a bar to extradition, since the requesting state should have the right to pursue criminal charges against persons who violate its laws regardless of nationality. The U.S. government accordingly extradites its nationals and seeks to limit nationality-based denials of its outgoing requests.13 In addition, U.S. statutory law expressly permits the Secretary of State to surrender a U.S. citizen to a foreign country when the extradition judge has issued a certification of extraditability and "the other requirements of [the applicable] treaty or convention are met."14
  • Prior proceedings (non bis in idem). These provisions, which appear in most extradition treaties, bar extradition where the person has already been convicted or acquitted in the requested state of the offense for which extradition is requested.15 The concept is similar to the U.S. doctrine of "double jeopardy."
  • Capital offenses. Although the United States tries to limit the application of this exception in its bilateral extradition treaties, many treaties contain provisions permitting the requested state to demand assurances that the death penalty will not be sought or imposed.16 For example, the U.S.-South Africa treaty provides that "[w]hen the offence for which extradition is sought is punishable by death under the laws in the Requesting State, and is not punishable by death under the laws in the Requested State, the Requested State may refuse extradition unless the Requesting State provides assurances that the death penalty will not be imposed, or if imposed, will not be carried out."17
  • Rule of specialty. The doctrine of specialty provides that "the requesting state may, after the fugitive has been surrendered to it, prosecute or punish the fugitive only for the crime or crimes for which extradition was granted, subject to certain exceptions."18 A common modern formulation of this doctrine, as explained by the U.S. Senate Committee on Foreign Relations in its report on the U.S. extradition treaty with Cyprus, is that "a person extradited under the Treaty may only be detained, tried, or punished in the Requesting State for: (1) the offense for which extradition was granted or a differently denominated offense based on the same facts, provided the offense is extraditable or is a lesser included offense; (2) an offense committed after the extradition; or (3) an offense for which the executive authority of the Requested State consents."19
  • Procedural and documentation requirements. Extradition treaties generally contain provisions that specify the documents and information required to support an extradition request, along with any translation and authentication requirements. Typically, the requesting state must provide information about the identity of the person sought (including specific descriptive information); the text of relevant laws; information about the facts and procedural history of the case; documentation relating to the charges or convictions; and any other information the parties have deemed necessary to evaluate the request. With respect to requests for extradition for a person sought from the United States, U.S. extradition judges have interpreted U.S. extradition treaties and statutory law as requiring evidence sufficient to, at minimum, support a finding of "probable cause" that the person is guilty of the charges pending in the requested state.20
  • Statute of limitations. Because statutes of limitations for particular offenses vary by country, many treaties include provisions specifying which country's statute of limitations will apply or, in some cases, providing that the passage of time is no bar to extradition. U.S. extradition treaties typically provide that the statute of limitations in the requesting state should be the only relevant limit.

Extradition Process

The extradition process in the United States (and in most other countries) involves both executive officials and judges who preside over extradition proceedings. In the United States, executive-branch responsibility for overseeing the extradition process is shared by the Department of State's Office of the Legal Adviser (specifically the Office of Law Enforcement and Intelligence) and the Department of Justice's Office of International Affairs (OIA), with substantial assistance from federal prosecutors around the United States.21 Extradition is proper only if an applicable extradition treaty is in place, all of its requirements are met, and none of its exceptions apply. Given the complexity and sensitivity of the issues involved, extradition is a time-consuming process, often taking years.

Extradition from the United States

Step 1: The Department of State receives and conducts an initial review of the extradition request.

The process begins when the requesting state sends an extradition request to the State Department through diplomatic channels.22 Upon receiving the request, the State Department determines whether (1) there is a treaty in force between the United States and the requesting state and (2) whether the request appears to meet the requirements of that treaty.23 It also forwards the documents to OIA so that OIA can conduct its own review.24 During this period, the State Department may ask the foreign government to clarify, supplement, or resubmit the request if the supporting documentation is incomplete or unclear.

Most modern extradition treaties allow the requesting state to seek "provisional arrest" of the subject while it prepares the formal request, which can reduce the possibility that a person will flee while the request is being finalized.25 The specific terms under which provisional arrest is permitted and the length of time a person can be held until a full extradition request is transmitted vary from treaty to treaty.

Step 2: OIA conducts a parallel sufficiency evaluation.

OIA conducts its own review of the request to verify that the request is complete and that the documents establish probable cause to believe that subject committed the crime charged.26 If the State Department and OIA jointly decide to pursue the extradition request, the State Department will formally transmit the original request and supporting documents to OIA, along with a declaration attesting that the request meets certain applicable treaty requirements.27

Step 3: OIA forwards the request to an appropriate U.S. Attorney's Office, which then seeks an arrest warrant.

If the request survives this initial review, OIA forwards the relevant documents to the U.S. Attorney's Office in the district in which the subject is located with instructions on how to proceed.28 That office assigns an Assistant United States Attorney (AUSA) to the case.29 The AUSA then files the appropriate papers in U.S. district court.30 According to the State Department, the practice "varies by district": "some prosecutors will file the extradition request when applying for the arrest warrant," while "others will merely refer to the request in the affidavit accompanying the application for the warrant and submit the actual request at the extradition hearing."31

Step 4: Proceedings before the extradition judge.

The individual then appears before a U.S. magistrate or district court judge for proceedings, generally including an initial appearance, bail determination, and hearing under 18 U.S.C. § 3184 (often called the "probable cause" hearing). In connection with the probable cause hearing, the extradition judge determines whether: "(1) [t]here is a treaty in force; (2) [t]he person arrested is in fact the person sought by the requesting state; (3) [t]he crime of which the fugitive is accused is an extraditable crime under the treaty; (4) [t]he request sets out probable cause to believe that the fugitive committed the charged crime; and (4) [t]here are no treaty grounds requiring denial of extradition."32 The specific issues addressed during the hearing depend on the provisions of the treaty and any defenses to extradition available under the law. Importantly, the probable cause hearing is not a trial on the merits, and the rules of evidence and criminal procedure do not apply as they would at a criminal trial.33 In general, individuals may offer "explanatory" evidence that provides an exculpatory explanation of the requesting state's evidence, but they are not generally permitted to offer evidence merely to contradict the evidence provided by the requesting state.34

Step 5: Certification by the extradition judge and decision by the Secretary of State.

If the extradition judge concludes that the request satisfies the probable cause standard and that the other requirements of the treaty are met, the judge will prepare a certification of extraditability and transmit the record of the case to the Secretary of State for a final decision on whether to order the extradition.35 The State Department's Office of the Legal Adviser then conducts a detailed review of the case. The Department "considers any written materials submitted to the Secretary of the State by the fugitive, his or her counsel, family, or interested parties."36 The Department also "will consider the likely treatment of the fugitive in the requesting country, including possible issues under the Convention Against Torture, as well as questions about political motivation."37 The Secretary has ultimate discretion to determine whether the subject should be released or surrendered.38

Certifications of extraditability are not directly appealable.39 Rather, the sole avenue for challenge is a petition for writ of habeas corpus.40 A court decision denying the petition may be appealed.41

Step 6: Notification and transit or release.

Once the Secretary of State decides whether an individual should be extradited, U.S. authorities will promptly notify the requesting state.42 Where the Secretary has ordered the surrender of the person sought for extradition, OIA—in coordination with officials of the requesting state—will arrange for the person's transfer to that country.43

Extradition to the United States

Step 1: Federal, state, or local prosecutor forwards extradition request to OIA.           

Requests for extradition are initiated by the prosecutor handling the potential prosecution in the United States and must be reviewed and approved by OIA before they are forwarded to the Department of State.44

Step 2: OIA conducts sufficiency review.           

OIA is responsible in the first instance for reviewing possible outgoing extradition requests, ensuring that they are legally sufficient, and deciding whether to ask the State Department to make a formal extradition request through diplomatic channels. After receiving a request, OIA, consulting with the State Department as needed, confirms the following:

(1) "[a]n extradition treaty is in force between the United States and the recipient country";

(2) "[b]oth countries' legal systems recognize the fugitive's crimes as criminal (dual criminality) and extraditable";

(3) "[t]he fugitive is procedurally extraditable, considering elements such as the citizenship of the fugitive and types of evidence that are available to the U.S. prosecutor"; and

(4) "[t]he applicable statutes of limitations governing the crimes in both the United States and the other country have not expired."45

OIA attorneys are the Department of Justice's subject-matter experts on extradition, and federal, state, and local prosecutors are required to route requests through OIA rather than directly contacting their foreign counterparts.46

Step 3: OIA forwards the request to the Department of State.           

If OIA determines that the request is sufficient, it forwards it to the Department of State for additional review.47 Because all requests for extradition must be sent through diplomatic channels, the request will proceed only if the Department of State agrees it is sufficient.48 If the request clears this second review, the Department of State will transmit an instruction to the appropriate overseas post.49

While the formal request for extradition is being prepared, the Justice Department may request the provisional arrest of the subject.50 Depending on the provisions of the relevant extradition treaty, detention under a provisional arrest warrant may be limited to a specific time period, such as 45 or 90 days. The person can be released if the United States does not submit a formal extradition request within the specified time period.51 Although a formal extradition request must be transmitted to the requested state by the Department of State, some modern treaties permit OIA to transmit a request for provisional arrest directly to the requested state's Justice Ministry.52

Step 4: The Department of State forwards the request to the requested state for extradition proceedings.           

The Department of State then sends the extradition documents to the U.S. embassy in the requested state, which will formally present them to the relevant ministry under cover of a diplomatic note.53 After receiving the request, competent authorities of the requested state undertake their own review. Procedures vary by country, but many countries' processes entail a review similar to that in the United States, including executive approval and review by a judge. Extradition determinations may be subject to appeal and, as in the United States, proceedings may take months or years to complete.54

Step 5: Notification and transit or release (or other disposition).           

Once the requested state reaches a decision regarding a U.S. extradition request, it will notify the U.S. government. If the request is denied, OIA may work with prosecutors and the Department of State to evaluate other options for obtaining custody of the individual, such as deportation.55

Defenses to Extradition

The intricate substantive and procedural requirements of the extradition process provide several possible defenses to extradition requests. Practitioners should remember that each extradition treaty is individually negotiated and that the analysis will turn on the provisions of the particular treaty in question. Some of the most common defenses include:

  • Not an extraditable offense/lack of dual criminality. The subject of an extradition request may argue that the charged crime (or, if applicable, the crime of conviction) is not covered by the treaty or that the principle of dual criminality is not satisfied. If the treaty is a "list treaty," the evaluation may be straightforward: if the offense is not on the list, the person sought for extradition prevails. As noted, however, modern treaties tend to use a "dual criminality" rather than "list" approach. Under a dual criminality approach, if the subject can establish that the conduct that is the basis of the extradition request is not a crime in both countries, the request will fail under the terms of the treaty.56
  • Sufficiency of the evidence. If the extradition request is based on pending criminal charges, the subject may argue that the information provided in the request fails to meet the required legal standard, which in the United States is probable cause (unless the treaty provides for a higher standard).
  • Political offense. As noted, extradition treaties generally include exceptions to the extradition obligation for "political offenses." Recent treaties have limited the political offense exception by providing that it does not apply to certain violent crimes.57
  • Other treaty-based defenses. An individual may raise defenses based on any other provisions of the applicable treaty, such as provisions regarding the statute of limitations, provisions limiting the extradition of nationals, provisions prohibiting extradition for capital offenses, and provisions permitting the requested state to decline to extradite based on humanitarian considerations relating to age or health. 
  • Human rights issues. The subject may argue that human rights concerns bar the extradition, most notably where there are concerns about a person's likely treatment if returned to the country seeking extradition. These issues fall to the Secretary of State, rather than the extradition judge, to decide. The State Department has sometimes been willing to place conditions on extradition to ensure that extradited persons receive legal protections to which they may not otherwise have been entitled in the requested state.58


Extradition is a lengthy and sometimes controversial process. Delays are especially common in high-profile cases involving allegations of political motivation or other improper considerations. Yet even the least controversial cases require in-depth analyses of the relevant treaty, the facts of the case, and the laws of both countries. Practitioners will be well-served by a working understanding of both the general extradition framework and the specific provisions of the treaty in question. Once this foundation is in place, the extended timeframes and unpredictable nature of many extradition cases provide the opportunity for creative counsel to seize on key developments to negotiate dispositions in favor of their clients, drawing on all parties' interest in avoiding the costs and burdens associated with a long and uncertain legal process.

© Arnold & Porter Kaye Scholer LLP 2020 All Rights Reserved. This Advisory is intended to be a general summary of the law and does not constitute legal advice. You should consult with counsel to determine applicable legal requirements in a specific fact situation.

  1. See William Booth, U-Md. professor testifies, amid glitches, at Assange extradition hearing in London, The Wash. Post (Sept. 7, 2020).

  2. See Mia Swart, Julian Assange extradition verdict to be delivered on January 4, Al Jazeera (Oct. 2, 2020).

  3. See Ben Taub, The Fight to Save an Innocent Refugee from Almost Certain Death, The New Yorker (Jan. 20, 2020).

  4. See Norway extradites jihadist preacher Mullah Krekar to Italy, BBC News (Mar. 26, 2020).

  5. See Spain orders detention of ex-head of Mexico oil firm pending extradition request, Reuters (Feb. 13, 2020).

  6.  See U.S. Dep't of State, 7 Foreign Affairs Manual (FAM) 1613.1(c). The State Department compiles an annual publication titled Treaties in Force, which contains the most up-to-date list of countries with which the United States has extradition treaties. See U.S. Dep't of State, Treaties in Force (last accessed November 10, 2020).

  7. Under U.S. statutory law, extradition generally is possible "only during the existence of any treaty of extradition with {the relevant} foreign government." 18 U.S.C. § 3181(a). Section 3181(b) provides a narrow exception authorizing the surrender of persons other than U.S. citizens, nationals, or permanent residents who have committed crimes of violence against U.S. nationals abroad, provided that the Attorney General makes certain certifications in writing.

  8. Although the United States has entered into a number of multilateral conventions that provide for extradition, "{a}s a matter of practice, the United States does not extradite, based solely on a multilateral convention, to a state with which we have no bilateral treaty." 7 FAM 1613.3(d).

  9. See 7 FAM 1642.1 (discussing mechanisms by which the United States may seek the deportation or expulsion of a person from another country); U.S. Dep't of Justice, Justice Manual (JM) 9-15.610 (same).

  10. See 7 FAM 1613.3(c).

  11. See 7 FAM 1613.3(a) ("The principle of 'dual criminality' . . . reflects the internationally accepted understanding that a requested state will only extradite a person for prosecution or punishment if the alleged or proven conduct, had it occurred in the territory of the requested state, would also be deemed criminal.").

  12. See, e.g.Extradition Treaty, U.S.-U.K., art. 4(2), Mar. 31, 2003, S. Treaty Doc. No. 108-23 (listing specific offenses that "shall not be considered political offenses," including "a murder or other violent crime against the person of a Head of State of one of the Parties, or of a member of the Head of State's family," and "an offense involving kidnaping, abduction, or any form of unlawful detention, including the taking of a hostage"). Another common approach is found in the 1998 U.S.-Korea extradition treaty, which excludes from the "political offense" exception any "offense for which both Contracting States have the obligation to extradite the person sought or to submit the case to their competent authorities for decision as to prosecution pursuant to a multilateral international agreement." Extradition Treaty, U.S.-S. Kor., art. 4(1), June 9, 1998, S. Treaty Doc. No. 106-2.

  13. See 7 FAM 1613.4(c) ("As a matter of policy, the United States no longer negotiates new extradition treaties if the partner country is unwilling or unable to commit to extradition of nationals.").

  14. 18 U.S.C. § 3196.

  15. See 7 FAM 1613.4(a).

  16. See 7 FAM 1613.4(e).

  17. Extradition Treaty, U.S.-S. Afr., art. 5, Sept. 16, 1999, S. Treaty Doc. No. 106-24.

  18. 7 FAM 1612.

  19. S. Exec. Rep. No. 105-23, at 66-67 (1998).

  20. The U.S. Supreme Court has described this standard as requiring "competent evidence to justify holding the accused to await trial, and not to determine whether the evidence is sufficient to justify a conviction." Collins v. Loisel, 259 U.S. 309, 316 (1922).

  21. See 7 FAM 1614.1(a), (c).

  22. See 7 FAM 1616(a) ("The request is generally made as a diplomatic note with accompanying documents, by the government's embassy in Washington, D.C., to the Department (L/LEI)."); JM 9-15.700 ("Foreign requests for extradition of fugitives located in the United States are ordinarily submitted by the embassy of the country making the request to the Department of State, which reviews and forwards them to the Criminal Division's Office of International Affairs (OIA).").

  23. See 7 FAM 1616(b).

  24. See 7 FAM 1616(b), 1634.1(a).

  25. See 7 FAM 1616(f).

  26. See 7 FAM 1634.1(c).

  27. See 7 FAM 1616(b), 1634.1(a)-(b); see also JM 9-15.700 ("The Department of State will separately verify in a transmission to OIA that there is a treaty in force between the United States and the country making the request, that the crime or crimes are extraditable offenses under the terms of the treaty, and that the supporting documents are properly certified.").

  28. See JM 9-15.700; 7 FAM 1616(c).

  29. See JM 9-15.700.

  30. See id.

  31. 7 FAM 1634.1(d).

  32. 7 FAM 1616(d); see also 7 FAM 1634.2(b).

  33. See JM 9-15.700; 7 FAM 1634.2(a); see alsoe.g.Skaftouros v. United States, 667 F.3d 144, 155 & n.16 (2d Cir. 2011).

  34. See 7 FAM 1634.2(c).

  35. See 18 U.S.C. § 3184; 7 FAM 1616(e), 1635.1(a); JM 9-15.700.

  36. 7 FAM 1635.1(b).

  37. Id.

  38. See 18 U.S.C. § 3186; United States v. Kin-Hong, 110 F.3d 103, 109 (1st Cir. 1997).

  39. See JM 9-15.700; 7 FAM 1634.2(f); see alsoe.g.Ordinola v. Hackman, 478 F.3d 588, 598 (4th Cir. 2007) (citing Collins v. Miller, 252 U.S. 364, 369 (1920)).

  40. See JM 9-15.700; 7 FAM 1634.3(a).

  41. See JM 9-15.700; 7 FAM 1634.3(c).

  42. See JM 9-15.700, 7 FAM 1634.2(g).

  43. See JM 9-15.700; 7 FAM 1614.2(b).

  44. See JM 9-15.210; 7 FAM 1615(b).

  45. See U.S. Dep't of Justice, Office of the Inspector General, Evaluation and Inspections Division, Review of the Office of International Affairs' Role in the International Extradition of Fugitives 14 (2002).

  46. See JM 9-15.210.

  47. See 7 FAM 1615(b).

  48. See id.

  49. See id.

  50. See 7 FAM 1615(e).

  51. See 7 FAM 1612.

  52. See JM 9-15.700.

  53. See JM 9-15.300.

  54. See id. ("Though factual defenses to extradition are limited, the fugitive may delay a decision through procedural challenges. The determination of extraditability is often subject to review or appeal. Prediction of the time required to return an individual to the United States is difficult and depends on the circumstances of the individual case and the practice of the foreign country involved.").

  55. See JM 9-15.600-650.

  56. The principle of dual criminality is especially relevant in cases involving complex or novel laws that do not have clear counterparts in other jurisdictions. For example, British national Richard O'Dwyer challenged his extradition to the United States for copyright violations by arguing that the alleged crime was not a violation of UK law. See The Government of the United States of America v. Richard O'Dwyer {2012} (U.K.).Although he did not prevail on his challenge in the UK proceedings, he was able to negotiate a deferred prosecution agreement with U.S. prosecutors. See United States v. Richard J. O'Dwyer, No. 1:10-mj-02471 (S.D.N.Y.) (docket reflecting entry of deferred prosecution agreement on December 6, 2012 and dismissal of complaint on June 7, 2013).

  57. For an example of the application of this principle, see the case of Mousa Mohammad Abu Marzook, in which a U.S. district court judge rejected the "political offense" argument of a Hamas leader sought for extradition by Israel on charges of murder, attempted murder, and conspiracy in connection with a number of shootings and bombings. U.S. judge rules Hamas leader can be extraditedCNN (May 8, 1996, 11:00 PM).

  58. See, e.g. Decl. of Clifton M. Johnson, Assistant Legal Adviser for Law Enforcement and Intelligence, Office of the Legal Adviser of the U.S. Dep't of State (Jan. 15, 2008) ¶ 8,  ("{I}n some cases, the Secretary might condition the extradition on the requesting State's provision of assurances related to torture or aspects of the requesting State's criminal justice system that protect against mistreatment. In addition to assurances related to torture, such assurances may include, for example, that the fugitive will have regular access to counsel and the full protections afforded under that State's constitution or laws.").