As the title suggested. if a man has sex with a girl he thinks is underage, but the girl is actually not, did he commit a crime?

I'd think he did, since I have seen a lot of cases where the police went undercover to arrest guys who think they are hooking up with underage girls. But I have read Wikipedia. which says "in jurisdictions with due process, there must be both actus reus ("guilty act") and mens rea for a defendant to be guilty of a crime (see concurrence)." so I might be wrong?

A very general question, but specifically wondering about cases in USA.

3 Answers 3



The age of consent to sex in the United States, in cases not involving child pornography (which is federally regulated as well as subject to state regulation) is a matter of state law, although federal law criminalizes crossing state lines for the purposes of sex with a minor in certain cases. There is moderate variation from state to state on this issue.

Many (probably most, but I haven't counted in a detailed survey) U.S. states have at least two separate components of a statutory rape law and a separate child prostitution law, to which different provisions regarding mistake of age apply.

One component of a typical state statutory rape law, which usually pertains to teenagers above a certain age, is a misdemeanor and includes a good faith mistake of age after reasonable investigation exception (at least if it does not involve commercial prostitution). This component also often has an "age gap" limitation for at least part of the age range that is sometimes a crime, to make sex not a crime if the couple are close in age (typically four years apart or ten years apart).

The other component of a typical state statutory rape law, which usually pertains to pre-pubescent minors, is usually a felony and does not have a mistake of age exception (this is sometimes called a strict liability statute even though you need to have an intent to do some things like an intent to voluntarily have sex). These laws have been upheld against constitutional due process challenges, at least as applied in particular cases. It is constitutional to have a statutory rape law with only a strict liability component. But it is relatively uncommon for a state to have such a law.

You need to know you are having sex with the person you think you are having sex with (if you were blindfolded and someone replaced your intended and believed partner with someone else without your knowledge, expectation, or consent, you would also be a rape victim, not a perpetrator and the child would be raped by the person arranging it even though you carried out the act unwittingly), but you don't constitutionally need to know that the person you are having sex with is under the statutory age and ignorance or mistake regarding the statutory age is no excuse.

In the U.S., state laws banning being a buyer of commercial prostitution by people under age eighteen, typically apply even if sex with that person would not be a crime if it was non-commercial, and typically do not have an exception for mistake of age, although statutes vary.

Also, many states, in addition to a statutory rape law also have a law prohibiting certain people who are in "positions of trust" such as teachers and coaches, from having sex with people under their supervision, even if by virtue of age alone, the statutory rape law would not be violated.

You can sometimes be guilty of attempting to commit a crime, or engaging in conduct believing certain facts to be true (as in the case of many child prostitution crimes), but plain vanilla statutory rape crimes are frequently not crimes for which an attempt is cognizable.


It would be an attempted crime (in layman's terms), which might be punishable (in law terms). You didn't say which jurisdiction, and there might be very subtle differences. If you want to have sex with a fifteen year old, but (a) her father stops you, or (b) she is actually 22, some countries might see both as an attempted crime, some might not.

I read in the USA, someone was convicted for trying to hunt protected animals outside the hunting season, but he actually got the date wrong and the hunting happened within the hunting season. It was proven beyond reasonable doubt that he intended to hunt illegally. That would be a reasonably comparable situation.

Or firing someone because they are gay is illegal in the USA and the UK, even if you were wrong and the person that was fired turns out not to be gay at all. That is explictely in the laws. It's actual illegal discrimination, not attempted illegal discrimination.

Some countries might have laws that make it explicitely illegal to have sex with people who you believe to be minors. I think in the USA child pornography covers pictures of men or women who are legal adults but look very young.

  • I believe child pornography in the US requires the participants to actually be minors or otherwise photos which are indistinguishable from actual photos of minors (e.g. exceptionally realistic CGI). There have been cases where an individual was charged with possession of child pornography because "experts" determined that the individual pictured was underage based on development of secondary sexual characteristics, but when the supposed child actually appeared and was able to prove that she was at least 18 at the time, the charges were dropped.
    – forest
    Commented Aug 27, 2022 at 2:17
  • The intent of laws relating to photorealism is to ensure that no one can claim that a photo is not really a photo. If it's obvious that it's not a photo, then it's legal, but if there's any doubt, then the assumption is that it is real.
    – forest
    Commented Aug 27, 2022 at 2:20

Yes, it’s a crime

The jails of the world contain many pedophilles who tried to have sex with 13 year old girls only to discover their online chat was with a 45 year old policeman.

  • 3
    however, most of these convicts sit not for that one act but for the countless illegal files that are confiscated after that sting.
    – Trish
    Commented Sep 17, 2020 at 13:05
  • 3
    @Trish Do you have any data to support this assertion?
    – bdb484
    Commented Sep 17, 2020 at 13:21
  • 4
    The question was “if a man has sex...” I think very few people are in jail for having sex with a 45 year old policeman who they thought was a 13 year old girl
    – gnasher729
    Commented Sep 17, 2020 at 13:54
  • Can you cite one actual example from the US?
    – user6726
    Commented Sep 17, 2020 at 17:12
  • 3
    @Trish those are child pornography cases, this is an attempted child prostitution or attempted statutory rape case. Not the same.
    – ohwilleke
    Commented Sep 17, 2020 at 20:04

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