What must a policeman have to legally enter your home without your permission?

To legally enter your home without your permission, a policeman must have a warrant. A warrant is a legal document issued by a judge that gives law enforcement the authority to conduct a search or seizure at a specific location. This requirement is in place to protect citizens' rights against unreasonable searches and to uphold the Fourth Amendment, which ensures that people's homes are secure from arbitrary intrusion by the government.

A warrant typically needs to be supported by probable cause, demonstrating to the judge that there is reasonable belief that evidence of a crime may be found at the location. This process is essential to ensure that law enforcement actions are legally justified and subject to judicial oversight.

While permission from a judge is part of the warrant process, simply having the judge's permission is not sufficient without the formal warrant itself. Similarly, a quest for evidence is ambiguous and does not grant police the authority to enter a home without consent or a warrant. A subpoena, on the other hand, is a legal order to appear or produce evidence in a legal proceeding, but it does not authorize police to enter a residence; it’s used in different contexts, typically regarding producing documents or appearance in court.