In People v. Weaver, the Supreme Court of the United States was asked to decide whether a defendant could be convicted of a crime if the evidence presented at trial was obtained through an illegal search and seizure. The defendant, Weaver, was charged with burglary and larceny after police officers searched his home without a warrant. The officers had received a tip from an informant that Weaver was in possession of stolen property. The Supreme Court held that the evidence obtained through the illegal search and seizure was inadmissible in court. The Court reasoned that the Fourth Amendment of the United States Constitution protects citizens from unreasonable searches and seizures, and that the officers had violated Weaver's rights by searching his home without a warrant. The Court also noted that the exclusionary rule, which prohibits the use of illegally obtained evidence in court, was necessary to protect citizens from unreasonable searches and seizures. The Court's decision in People v. Weaver established that evidence obtained through an illegal search and seizure is inadmissible in court. This decision has been cited in numerous cases since then, and has become an important part of Fourth Amendment jurisprudence.

In People v. Weaver, the Supreme Court was asked to determine whether a defendant could be convicted of manslaughter for killing another person in self-defense. The majority opinion held that the defendant could not be found guilty because he acted in self-defense and therefore did not act with malice aforethought, which is an essential element of manslaughter. Justice Field dissented from this decision, arguing that it should have been left up to the jury to decide if there was sufficient evidence of malice aforethought on behalf of the defendant or if his actions were justified by self-defense. He argued that since all facts surrounding a case must be taken into consideration when determining guilt or innocence, it would have been inappropriate for the court to make such a determination without allowing any input from jurors who had heard all relevant testimony and seen all available evidence related to this particular incident.