What must police have to search a property without a warrant?

The requirement for police to search a property without a warrant centers primarily on the concept of "probable cause." Probable cause is a legal standard that suggests there is a reasonable belief, based on factual evidence, that a crime has occurred or is happening, which justifies the police entering the property. This means that the officers must have sufficient facts or circumstances that would lead a reasonable person to believe that evidence of a crime can be found in that location.

While consent from the property owner can also allow for a warrantless search, it is not the only avenue available to law enforcement. In situations where a crime is actively occurring, police may be permitted to act quickly in order to prevent the destruction of evidence or ensure public safety. This is separate from the need for probable cause, as the urgency of the situation might justify immediate action without a warrant.

The option regarding a valid search warrant from a judge is synonymous with the traditional requirement for searches but doesn't apply in cases where law enforcement relies on probable cause or exigent circumstances to conduct a search without first obtaining a warrant. Thus, probable cause is at the core of what law enforcement must demonstrate to justify a warrantless search.