18 U.S. Code § 3559.Sentencing classification of offenses
https://www.law.cornell.edu/uscode/text/18/3559
is classified if the maximum term of imprisonment authorized is—
life imprisonment, or if the maximum penalty is death, as a Class A felony;
twenty-five years or more, as a Class B felony;
less than twenty-five years but ten or more years, as a Class C felony;
less than ten years but five or more years, as a Class D felony;
less than five years but more than one year, as a Class E felony;
one year or less but more than six months, as a Class A misdemeanor;
six months or less but more than thirty days, as a Class B misdemeanor;
thirty days or less but more than five days, as a Class C misdemeanor; or
five days or less, or if no imprisonment is authorized, as an infraction.
(F)the term “serious violent felony” means—
a Federal or State offense, by whatever designation and wherever committed, consisting of murder (as described in section 1111); manslaughter other than involuntary manslaughter (as described in section 1112); assault with intent to commit murder (as described in section 113(a)); assault with intent to commit rape; aggravated sexual abuse and sexual abuse (as described in sections 2241 and 2242); abusive sexual contact (as described in sections 2244(a)(1) and (a)(2)); kidnapping; aircraft piracy (as described in section 46502 of Title 49); robbery (as described in section 2111, 2113, or 2118); carjacking (as described in section 2119); extortion; arson; firearms use; firearms possession (as described in section 924(c)); or attempt, conspiracy, or solicitation to commit any of the above offenses; and
(ii)
any other offense punishable by a maximum term of imprisonment of 10 years or more that has as an element the use, attempted use, or threatened use of physical force against the person of another or that, by its nature, involves a substantial risk that physical force against the person of another may be used in the course of committing the offense;
(d)Death or Imprisonment for Crimes Against Children.—
(1)In general.—Subject to paragraph (2) and notwithstanding any other provision of law, a person who is convicted of a Federal offense that is a serious violent felony (as defined in subsection (c)) or a violation of section 2422, 2423, or 2251 shall, unless the sentence of death is imposed, be sentenced to imprisonment for life, if—
(A)
the victim of the offense has not attained the age of 14 years;
(B)
the victim dies as a result of the offense; and
(C)
the defendant, in the course of the offense, engages in conduct described in section 3591(a)(2).