A warrant, in the context of law enforcement, is a legal document issued by a judge or magistrate that authorizes police to take a specific action, such as searching a property or making an arrest. This document is based on probable cause, meaning there is reasonable belief that a crime has been committed or that evidence of a crime can be found in the specified location. Warrants are essential for protecting individual rights under the Fourth Amendment of the U.S. Constitution, which guards against unreasonable searches and seizures. They ensure that law enforcement actions are conducted legally and with oversight, maintaining a balance between public safety and personal privacy.