Lets say that I commit a crime in which the USA and another country both have jurisdiction. As an example I, a US citizen, kill Bob, a citizen of country X, while we're located in Antartica.

Country X catches me first and puts me on trial; they refuse to extradite me to the USA when asked. However, for some reason X has some bizzare rules that makes them far more lenient towards my crime - maybe the leaders X are all horrible racists towards Bob's race, which means it's both more likely that I will be found 'innocent' of the crime despite my having done it and I face a drastically lower penalty if found guilty.

Eventually some time after the trial I return to the USA. The local authorities would like to see me face a harsher penalty for my crime. I'm wondering if they have any way to try or imprison me under these circumstances:

  1. I was put on trial but found not guilty of the crime
  2. I was found guilty, spent 2 weeks in jail and paid a 50 dollar fine
  3. I was found guilty of a crime for my actions, but the crime was different from the crime as the USA would define it (for instance the country is so horribly racist they don't consider killing a member of Bob's race murder and instead tried me on something else like animal cruelty).

Would it matter if the countries have an extradition treaty, or if the crime was something other than murder, like bribery or grand theft?

  • 8
    When it comes to two countries having jurisdiction, it becomes more of a political matter than a legal one. A country prosecuting a person after they've already gone on trial for that crime in another country is essentially saying that they don't recognize or respect the other country's legal system. In most cases, that would be a very bad political move. I'd be interested in the legal aspect, though. I know many extradition treaties explicitly forbid this, but if the person isn't extradited (returns on their own) then that doesn't really apply.
    – animuson
    Commented Aug 18, 2017 at 18:37

4 Answers 4


You can be prosecuted for the crime in the U.S., both at the federal level and at the U.S. state level (or both), completely without regard to what happened in the criminal justice process elsewhere.

This is true in all of the scenarios you pose, for any offense, and with or without an extradition treaty (of course, unless the treaty had some anomalous provision to the contrary or deprived the U.S. of jurisdiction by statute rather than constitutionally of this crime).

The U.S. Supreme Court determined in Heath v. Alabama, 474 U.S. 82 (1985) that the double jeopardy clause of the U.S. Constitution is applied separately with regard to each sovereign involved and that each state and the federal government count as separate sovereigns. In the pertinent part, it states:

The dual sovereignty doctrine is founded on the common law conception of crime as an offense against the sovereignty of the government. When a defendant in a single act violates the "peace and dignity" of two sovereigns by breaking the laws of each, he has committed two distinct "offences." United States v. Lanza, 260 U. S. 377, 260 U. S. 382 (1922). As the Court explained in Moore v. Illinois, 14 How. 13, 55 U. S. 19 (1852), "[a]n offence, in its legal signification, means the transgression of a law." Consequently, when the same act transgresses the laws of two sovereigns, "it cannot be truly averred that the offender has been twice punished for the same offence, but only that by one act he has committed two offences, for each of which he is justly punishable." Id. at 55 U. S. 20.

In practice, the U.S. Justice Department and most state and local prosecutors are disinclined to prosecute a crime that has already been handled by another jurisdiction and often have official, but non-binding, policies to that effect. In part, this is because an acquittal in one jurisdiction makes it likely that it is a weak case, while a conviction in one jurisdiction often constitutes sufficient punishment.

There could be an issue under the 8th Amendment to the U.S. Constitution (cruel and unusual punishment) over whether a punishment imposed in a U.S. conviction for a crime needs to consider the already severe punishment imposed in another jurisdiction for the same crime in order to prevent the cumulative punishment from being cruel and unusual. But, I am not aware of authoritative case law that resolves that constitutional question.

Certainly, evidence of a prior punishment for the same offense could be presented at a sentencing hearing following a conviction in mitigation of the punishment that should be imposed. Indeed, in some states time served pursuant to a conviction for the same crime in another jurisdiction might statutorily count as "time served" for which the defendant is legally entitled to credit at sentencing.

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    For an example of one of these non-binding policies, here's the federal government's. TL;DR: There need to be good reasons and an Assistant AG has to approve, but if the policy is violated it's up to the DOJ how or whether to respond.
    – cpast
    Commented Aug 18, 2017 at 19:53
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    So as between Calfornia and the United States, OJ Simpson could have been prosecuted by the "second" sovereign, which chose not to?
    – Libra
    Commented Sep 24, 2017 at 15:51
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    @TomAu Correct, assuming that there is a relevant federal offense, which there may well not have been. A great many murders are independently covered by federal crimes, but not all of them.
    – ohwilleke
    Commented Sep 24, 2017 at 20:04
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    You did forget one reason that separate sovereigns do not usually prosecute for the same crime. Court costs money. So to save the cost of doing it over, the Feds will let the state justice system handle the case and be done with the matter.
    – hszmv
    Commented Aug 23, 2022 at 10:32

Yes. Not only could the US prosecute you if another country already tried you, it can prosecute if one of the 50 states already tried you. US courts have treated the rule against double jeopardy as a rule against two prosecutions by the same sovereign. But a US state is a separate sovereign from the feds and from other states, and the US is a separate sovereign from other countries. The introduction of this paper gives a decent overview of double jeopardy with multiple sovereigns (the later parts analyze the rules of one court is national and the other is international), where you can see that the U.S. isn't the only country that can prosecute you after another country has already tried you for the same conduct.

  • This actually happens, too. Often, a state will acquit a white person of the muder of a non-white person, and then the feds will prosecute the suspect for violating the victim's civil rights (by killing them). See for example the final paragraph of this story.
    – Kevin
    Commented Aug 19, 2017 at 0:44
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    @Kevin That story is specifically about police officers. No mention is made whether this occurs 'often', so your comment is needlessly damaging.
    – Mast
    Commented Aug 19, 2017 at 8:06
  • @Kevin This also raises an important question: What is "the same" crime under different jurisdictions in the first place? E.g., I suppose that "merely" violating civil rights is not under capital punishment. More generally, is whatever law deals with killing people in country X about the "same" crime as a somewhat similar law in country Y? What if X sues for murder and Y sues for manslaughter? What if I set a house on fire and that kills an inhabitant, and country X sues for arson and country Y sues for murder (and the owner of the house sues for damages)? Commented Aug 20, 2017 at 13:43
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    @Hagen At the federal level, deprivation of rights under color of law is a capital crime if the crime results in a death.
    – cpast
    Commented Aug 20, 2017 at 13:56
  • What @cpast is describing can also be found through the Felony Murder rule, which holds that if you commit a felonious crime and someone dies because of a result of your crime, that death is treated as a first degree murder (you rob a bank, but plan not to kill anyone. You point your guns at the ceiling and shout "No Body Move, this is a stick up." The shock of this causes a little old lady to have a fatal heart attack... congrats, you're now a murder. +
    – hszmv
    Commented Aug 23, 2022 at 10:41

Generally, yes, you can be prosecuted by the federal government if what you did broke a federal law, even if another entity has prosecuted you.

However, if we tweak the facts of your hypothetical a little, we run into an exception to the general rule. Let's change the victim to a fellow US citizen, and change the murder location to country X instead of Antarctica. The murder is now a violation of 18 U.S. Code § 1119 - Foreign murder of United States nationals, but that particular law has some unique restrictions that may interest you:

No prosecution may be instituted against any person under this section except upon the written approval of the Attorney General, the Deputy Attorney General, or an Assistant Attorney General, which function of approving prosecutions may not be delegated. No prosecution shall be approved if prosecution has been previously undertaken by a foreign country for the same conduct.

No prosecution shall be approved under this section unless the Attorney General, in consultation with the Secretary of State, determines that the conduct took place in a country in which the person is no longer present, and the country lacks the ability to lawfully secure the person’s return. A determination by the Attorney General under this paragraph is not subject to judicial review.

If you've been acquitted or made to pay a small fine by country X, then, by the letter of the law, you cannot be prosecuted under this law.

If you were convicted of animal cruelty, that shows they clearly had the ability to put you on trial, and prosecution under this law would appear to be against the intent of the law (and arguably the letter of the law too, if it can be considered the "same conduct" even if it's not the same crime.) I'm not sure it's ever come up; you apparently need two cabinet members involved whenever you use this law, so I assume it's rarely used.

This wouldn't preclude some other federal law being used to prosecute you - but, if it happened outside the US, it's very possible that no other federal law applies.

Would it matter if the countries have an extradition treaty, or if the crime was something other than murder, like bribery or grand theft?

One of the determinations required for prosecution is that "the country lacks the ability to lawfully secure the person’s return", so yes, an extradition treaty seem relevant to that. And these prosecutorial restrictions only apply to this particular law against foreign murder of US nationals, so yes, the crime matters.

  • So if a US citizen murders another US citizen in Germany, if you is caught and sentenced in Germany the USA will not prosecute him, but if he flees from Germany back to the USA before being prosecuted they will prosecute him? (Especially if Germany can't figure out who the murderer was, and therefore cannot ask for an extradition).
    – gnasher729
    Commented May 5, 2018 at 13:35
  • That seems like a stretch, but the courts aren't allowed to review that determination, so I guess it's up to the attorney general as to how to interpret it.
    – D M
    Commented May 5, 2018 at 16:15

With respect to extradition, the U.S. will only sign Extradition Deals where extradition can only be enforced if both countries have a similar enough crime. Being Prosecuted for a Crime that the U.S. wants you for is probably the worst thing to happen when fighting extradition to the United States. The one thing that can stop a murder case from extradition from Australia is that the latter does not have the death penalty while the former does. But it's more of hiccup than a hurdle as the Aussies will be more than happy to turn the guy over if the United States if the Prosecutor's office assures they will not seek the death penalty for this particular case. The reverse also happened when the U.S. refused to extradite Amanda Knox to Italy to stand for a second trial in a murder case in which she was originally found guilty. This is legal in Italy but as far as the United States was concerned, they had no prosecutor jurisdiction beyond the extradition and she had already been acquitted of the crime once, attaching Double Jeopardy to the case. Because of this, the second trial had no legal basis in the United States, so they refused the request.

Additionally, if the Jurisdiction is between two similar enough nations, the United States might choose to file for Extradition after the verdict is handed down. The United States solves most of it's criminal cases (90-95% by plea bargain and if the Australians satisfy the sentence the he would likely get in the U.S., than they won't bother... you can only give one life sentance to a man after all. However, should he make parole, the U.S. could still try him for the crime here.

  • This is a rather confusing answer, and I don't see how it answers the question - it seems to talk about extradition.
    – sleske
    Commented Aug 3, 2018 at 8:02

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