Final answer:
A search warrant is the legal document that grants permission to search a specific location for evidence of a crime, which must be signed by a judge and is based on probable cause.
Step-by-step explanation:
The permission to look for evidence of a crime in a particular location is called a search warrant. This legal document, signed by a judge, allows police to search and/or seize persons or property.
However, there are exceptions where police can act without a warrant, such as when the owner consents, when they expect evidence may be destroyed (exigent circumstances), or when items are in plain view.
The probable cause standard is used to justify the issuance of a search warrant, meaning there must be reasonable grounds to believe a crime has been committed or evidence will be found. It's also important to note from the Mapp v. Ohio case that evidence obtained illegally without a warrant and not under the established exceptions cannot be used in court, under the exclusionary rule.