Crime against nature

The crime against nature or unnatural act has historically been a legal term in English-speaking states identifying forms of sexual behavior not considered natural or decent and are legally punishable offenses. Sexual practices that have historically been considered to be "crimes against nature" include anal sex and bestiality.

For much of modern history, a "crime against nature" was understood by courts to be synonymous to "buggery", and to include anal sex (copulation per anum) and bestiality. Early court decisions agreed that fellatio (copulation per os) was not included, though mainly because that practice was virtually unknown when the common-law definition was established (it remained so rare that first attempted fellatio prosecutions under the "crime against nature" statute date to 1817 in England and 1893 in the United States.) Likewise, sexual activities between two women were not covered. Over time, particularly starting in the early 20th century, some jurisdictions started enacting statutes or developing precedents the extended the scope of the crime to include fellatio and, sometimes, other sexual activities.

The term crime against nature is closely related to, and was often used interchangeably with, the term sodomy. (This varied from jurisdiction to jurisdiction. Sometimes the two terms were understood to be synonymous; sometimes sodomy was limited to sexual activities between two humans; and sometimes sodomy was taken to include anal sex or bestiality, whereas crime against nature also included fellatio.)

Until the early 19th century, courts were divided on whether the act needed to be completed (to result in ejaculation) in order to be a punishable offense. This question was deemed sufficiently important that, in 1828, English law was explicitly amended to specify that proof of ejaculation was not necessary for convictions for buggery and rape. The crime was not limited to same-sex activities, and, in case of an act between two adults, both participants were guilty, regardless of consent. Attempted or completed act of sodomy, committed by a husband against his wife, was grounds for divorce in common law.

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