Final answer:
The Fourth Amendment requires the police to have a warrant to search someone's property.
Step-by-step explanation:
The amendment that requires the police to have a warrant to search someone's property is the Fourth Amendment of the United States Constitution. According to the Fourth Amendment, individuals have the right to be secure in their persons, houses, papers, and effects against unreasonable searches and seizures. This means that government officials, including the police, need to obtain a warrant based on probable cause before they can search someone's property.