based off of the answer to this question: If one leaves the US to commit an act illegal in the US but legal in the country they travel to are they guilty of a crime? My first bizarre loophole question has to do with situations when someone is a US citizen, but consider themselves to be citizens of a different country with different laws..

Lets say you have two Individuals Bob, age 17, and Alice, who just turned 18, who live in, and are citizens of, some non-US country X, who are dating and have a sexual relationship. Say country X considers the age of consent 16, recognizes dual citizenship, and has an extradition treaty with the US...

However, Alice happened to have been born on a cruise while the cruise ship was sailing through US territorial waters, thus making her a US citizen. She has never done any of the things which can cause someone to officially lose their US citizenship.

Federal law states it is illegal for a US citizen to have sex with an individual under the age of 18 in a 'foreign place'

I'm wondering what, of any of these scenarios, would be illegal due to the above law and could theoretically lead to either extrication, or to arrest when/if they ever visited the US at some later date (and if one is possible but not the later).

  1. Alice never realizing she was born actually born in US waters and never thinking of herself as a US citizen, and she never visited the US or engaged in any of the activities that cause her to lose citizenship

    If the above would not be sufficient would any of the below situations potentially lead to prosecution:

    • Knew she was also a US citizen and had once claimed some minor right or privileged due to being a US citizen.
    • Occasionally visits a friend or relative within the US for brief periods, using her US citizenship to allow easier entry to the US, without going through the steps of the VWP.
    • Once stayed in the US with said friend/relative for slightly more then 90 days (beyond the length a regular tourist can stay) many years ago
    • Had just spent spent 91 day summer vacation with her family relative before returning to her home country and having sexual relations with Bob.
  2. Alice and Bob both live in and were citizens of X but originally met when both were on a vacation to the US, ultimately having a sexual relationship in their home country.

    Would Alice potentially face prosecution, if not would this change if:

    • The couple had (legally) engaged in sexual activity in the US prior to traveling back home
    • The couple originally met in a state where sexual intercourse would have been illegal and so waited until returning home before having a sexual relationship?
    • Alice bought bob plan ticket home, so she is officially 'transporting' bob? (section a of the above law applies)
    • Alice and bob did have a relationship prior to their visit to the US which continued during their US visit.

I realize that prosecutor discretion would usually result in no one choosing to prosecutor most if not all of the above cases, despite any legal right, but I'm asking rather they could face charges if a prosecutor did choose to move forward for some reason. I don't know why they would, maybe they are angry at Alice for some other legal act and this is their way of bending the laws to punish Alice in some way, maybe someone is putting pressure on Alice as some political maneuver to pressure her important father into something, maybe some prosecutor is just really gung-ho in prosecuting crimes for some reason whatever...

*Edit: Looking back at the law I linked I realized that the definition of illicit sexual encounter, when outside of US territories, is effectively defined as a commercial sexual act, which negates all my examples since no one was being payed. However, I'm not interested in the specific law so much as how any law making activities on foreign territory illegal would be applied to citizens, and only used this law because it was the only one I knew of to reliable reference. For now umm...just pretend that illicit sexual act part of the law was not limited only to commercial acts when answering this question? I think the heart of what I'm trying to understand wouldn't change if that law were slightly different and that's easier then my rewriting all of the above.

ps. A US citizen can travel to Angola and have sex with a 12 year old without any repercussion so long as he doesn't pay anyone if I'm reading the law right? That's something I really didn't need to know about. I knew I shouldn't have used that particular law as my example for this...

pps. Also the definition of "any person can be charged with a criminal offense" seems extremely vague since it doesn't specify what country/state laws would apply for deciding if the person could be charged with a criminal offense, and I'm sure if you look far enough countries have outlawed all kind of things as sexual offenses, like being in the presence of a women who isn't wearing a hijab.

  • 4
    Note 2: Your reading of "illicit sex act" is not correct. 18 USC 2423(f)(1) says it includes acts with someone under 18 which would be illegal under chapter 109A if they were committed in special maritime and territorial jurisdiction. Per 18 USC 2241(c), this includes sex with anyone under 16 who is at least 4 years younger than you, and anyone under 12 period.
    – cpast
    Oct 22, 2015 at 2:59
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    @YviDe: No. Citizenship and nationality are purely matters of law. Who is a citizen and national of each country are solely determined by the laws of that country. It's not up to anyone to "claim" or "not claim" except as provided by the country's law.
    – user102008
    Oct 24, 2015 at 7:45
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    @cpast: Most countries will not extradite anyone for something that isn't a crime in the country that is supposed to do the extraditing.
    – gnasher729
    Oct 30, 2015 at 23:09
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    @derTruth Correct. For being born in a US territory to make someone a US citizen, the person's parents have to be in the US without enjoying diplomatic immunity. For everyone else, being born in US territory makes them a US citizen.
    – phoog
    Jan 25, 2016 at 22:59
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    Props to Alice's mother for whatever "lean in"-style thinking led her to go on a cruise with a baby about to pop.
    – jez
    Aug 18, 2017 at 16:02

4 Answers 4


Ignorantia juris non excusat

You can say I didn't know: it won't keep you out of jail.

Rather than delving into the specifics of your question, I will keep my answer general. If you break the law, you break the law. It doesn't matter if:

  • you don't know what the law is,
  • you didn't think the law applied to you,
  • you thought what you were doing was in accordance with the law.

"Break the law" is an objective fact - there is no subjectivity involved. The state of mind of the person is, in most jurisdictions, irrelevant; the common law doctrine of mens rea or "the guilty mind" has almost universally been done away with.

Now specific offences have specific defences. Generally, in underage sex cases genuine ignorance of the age of the person is one such defence. A court may decide that ignorance that the person was underage under US law may qualify for this defence.

  • 17
    Sorry to necrocomment, but I am not entirely sure if ignorantia juris non excusat fully applies here. If Alice did not know she was a US citizen at all this would appear to be a mistake of fact as opposed to ignorance of law?
    – Vality
    Jan 13, 2017 at 20:43
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    Following on to Vality, we could specify that while Alice's citizenship is a combined matter of fact and law, if she were genuinely under the impression that the ship was in international waters at the time of her birth, and she was unaware of any other fact that would result in her being a US citizen, then it would be purely a case of ignorance of the facts. Oct 15, 2018 at 22:08
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    I thought Mens Rea was enshrined in law as the basis for law... Mar 10, 2019 at 2:01
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    @DaleM One of the original common law jurisdictions (England and Wales) has not been fully codified - murder is still a common law offence. I believe Mens rea applies to codified laws too. Oct 6, 2019 at 7:21
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    @DaleM: That's pretty much the definition of "subjective". The judge has to figure out how the law applies to this exact scenario (no law covers all of them) and the jury has to figure out what the "real truth" is, which is impossible.
    – MichaelS
    Jan 15, 2022 at 7:16

One line for Alice to pursue, is that in general a country will not extradite someone (even a citizen of the country requesting extradition) on charges that are not a crime in that country. Country X won't hold a full criminal trial to establish this, but they will have some standard (which varies according to what extradition treaties they have with the US) that extradition charges must meet in order to be considered.

irth's answer contains a case that may or may not be an exception to this rule (I don't know whether it was ruled that he would be extradited despite nothing having been done that Canada considers an offence, or whether Canada found a way to construe what he was charged with as being an offence). But even if the general principle doesn't always hold in Canada and didn't help that person, it may still be relevant to Country X and to Alice.

So, if the act is a crime in country X then since it occurred in country X on the whole X won't extradite because they will instead prosecute. And if the act is not a crime in country X then Alice may hope that X declines to extradite. This depends entirely on the law of country X (well, plus I suppose any diplomacy the US might bring to bear against X to "encourage" a particular verdict). Firstly they must refuse to extradite such cases, and secondly they must determine that Alice's US citizenship does not alter the relevant age of consent for her. Even if she wins, it's still not an ideal outcome for Alice. She may find herself unable to visit any countries in which her act would be a crime, for fear that unlike X they would indeed arrest and extradite her to the US.

So for example, suppose the US were to make it a crime for any US citizen to reside abroad (never mind whether that's constitutional: let's just say the US changes the constitution too if necessary!). Then one would not expect every country of the world to arrest and extradite all US citizens resident in that country, and especially not to do so for their own nationals who are US dual citizens. I've exaggerated the situation to something that quite clearly other countries do not considers a crime, just to remove any doubt that country X would consider the charges in the extradition request to be non-crimes.

  • Country Y will say "please extradite Alice because she did ...", and country X has to just check whether what Alice is accused of would be prosecuted in X. That would just involve looking up some law books.
    – gnasher729
    May 15, 2023 at 8:30

A perhaps better example of the general principle. It is illegal under US law for US citizens to engage in commercial bribery in a non-US country, even if such acts are not illegal under local law. (I believe that the UK has a similar law.) The country where the bribery took place might or might not extradite a person charged with such an act, but many other countries surely would, and if such a person were to visit the US s/he could surely be arrested.

This avoids the complications of laws about sexual acts.


As cpast already pointed out in the comments, it would not actually be illegal under US law for an 18 year old US citizen to have sex with a 17 year old in a country whose local law permits such sexual relationships. Bob would need to be under the age of 12, or Bob would need to be under the age of 16 with Alice being at least 4 years older than Bob, in order for the US law in question to apply.

If Alice were 20 and Bob were 15, then it would be illegal under US law for Alice, being a US citizen, to have sex with Bob while outside the US.

I'll address the issue of extradition momentarily. If Alice is in the US and is prosecuted by the US for the offence, Alice can probably use the fact that she didn't know she was a US citizen as a defense against 18 USC §2423(c). In Kawakita v. United States (1952), the government was required to prove that Kawakita knew he was still a US national at the time when he committed the alleged acts, because only US nationals can commit treason against the US. Rehaif v. United States (2019) concerned a law where one of the elements of the offense is not being a US national, and in fact not having a lawful status in the US. In that case, the Supreme Court held that the government must prove that Rehaif knew that he didn't have a lawful status.

However, the government could argue in the case of Alice that having US citizenship or lawful permanent resident status is a jurisdictional element of an offense under §2423(c) rather than a material element, thus distinguishing Alice's case from Kawakita and Rehaif. The prosecution is not required to prove that the defendant had knowledge of a jurisdictional element. For example, if you're smoking marijuana while strolling through a forest in Canada, and you happen to step into the United States without knowing that you've stepped into the United States, you can be convicted under US law despite the fact that you didn't know you were in the US. So, if US citizenship is held to be a jurisdictional element in §2423(c), Alice could be convicted without the government needing to prove that she knew she was a US citizen. (To be honest, I'm not sure how to tell whether it's a jurisdictional or material element. I'm not a lawyer and I've never been to law school. I imagine this is one of those things they teach people in law school, only for most students to forget shortly after passing the bar exam.)

Regarding extradition:

If the act is legal under local law

Extradition is generally not required in cases where the act upon which the extradition request is based is legal under local law (the so-called dual criminality doctrine). However, some countries' laws do permit (not require) the authorities, at their discretion, to extradite people for acts that are legal under local law.

If the act is illegal under local law

Alice will generally be tried and punished under the law of the country where the offence occurred. Extradition treaties and domestic extradition laws usually don't require extradition in such circumstances, i.e., the country where the offence occurred is not required to extradite Alice for the purposes of having her tried and punished a second time in the requesting country. Again, some countries probably permit (but do not require) the authorities to approve a request to extradite someone out of the country under such circumstances.

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