What must be shown for a warrant to be issued according to the Fourth Amendment?

For a warrant to be issued according to the Fourth Amendment, it is essential to establish "probable cause supported by oath or affirmation." This means that law enforcement must demonstrate a reasonable belief that a crime has been committed and that the evidence related to that crime can be found in the location specified in the warrant. This requirement is designed to protect individuals from unreasonable searches and seizures by ensuring that a neutral party, typically a judge or magistrate, evaluates the evidence and finds it sufficient to justify issuing the warrant. The "oath or affirmation" aspect underscores the importance of truthfulness in the information presented to the issuing authority, providing an additional layer of accountability.

Establishing probable cause is fundamentally different from mere permissions or opinions; it involves providing specific facts and circumstances that lead law enforcement to believe that a search is justified. This mechanism serves to balance effective law enforcement with citizens' rights to privacy and due process.