Cannibalism is the nonconsensual consumption of another human's body matter. In the United States, there are no laws against cannibalism per se, but the act of cannibalism would probably violate laws against murder and against desecration of corpses.
The British formally outlawed cannibalism in the early 1800s. By most accounts, it was the spread of Western religion and law into pre-industrial societies that extinguished many cannibalistic practices. In countries with established legal infrastructure—that is, in which they were economically successful enough to afford courts—cannibalism had already been made rare.
One case in which nonconsensual survival cannibalism takes center stage is taught in most every criminal law course: Regina v. Dudley and Stevens. In Dudley, two upstanding naval citizens, Dudley and Stevens, along with their shipmates Brooks and Parker, were marooned on a raft after their vessel, the Mignonette, was destroyed in a storm. They had no fresh water on the raft, and just two cans of turnips. They managed to fight off a shark attack and capture and eat a sea turtle, but they ended up starving and thirsting for many days. The youngest and weakest, Parker, buckled and drank sea water, which made him sick with dehydration. After Parker went comatose, Dudley killed him and the survivors drank his blood and ate his meat for the next week before being rescued. The judges in that case did not accept the necessity defense and sentenced the defendants to death. Judge Posner defends the Dudley convictions, arguing that enforcing criminal penalties for cannibalism forces the perpetrators to kill only if the circumstances are so drastic as to make murder worth the later punishment.
In 2001, a German named Armin Miewes placed an online solicitation for “a boy, if I can real kill him and butchering him. I am a cannibal, a real cannibal.” The respondent, Bernd Brandes, had sex with Miewes before asking Miewes to cut off his penis. Miewes complied, whereupon he fried the penis and the two ingested it together. Miewes then killed Brandes with Brandes’s consent, afterwards dismembering the body and freezing it for later consumption. Miewes was later arrested, by which time he had ingested approximately 20 kg of Brandes’ body. Cannibalism was not illegal in Germany in 2001, but Miewes was nonetheless convicted of killing by request and defiling a corpse, for which he received a sentence of 8.5 years.
 Travis-Henikoff 282.
 Sanday 210.
 Stephanie Miller, Cannibalism and the Common Law (1984).
 Richard A. Posner, An Economic Theory of the Criminal Law, 85 Colum. L. Rev. 1193, 1229-30 (1985).
 Roger Davis, You Are What you Eat: Cannibalism, Autophagy, and the Case of Armin Meiwes, Territories of Evil 151 (2008).