18 USC 2242 - Sexual abuse

Whoever, in the special maritime and territorial jurisdiction of the United States or in a Federal prison, or in any prison, institution, or facility in which persons are held in custody by direction of or pursuant to a contract or agreement with the head of any Federal department or agency, knowingly
(1) causes another person to engage in a sexual act by threatening or placing that other person in fear (other than by threatening or placing that other person in fear that any person will be subjected to death, serious bodily injury, or kidnapping); or
(2) engages in a sexual act with another person if that other person is
(A) incapable of appraising the nature of the conduct; or
(B) physically incapable of declining participation in, or communicating unwillingness to engage in, that sexual act;

or attempts to do so, shall be fined under this title and imprisoned for any term of years or for life.