Michigan v. Tyler

A Fourth Amendment search occurs whenever the government intrudes on a reasonable expectation of privacy. All entries are presumed illegal if no warrant is obtained. The Court has recognized several exceptions to this rule. A burning building presents an emergency of sufficient proportions to render a warrantless entry under the Fourth Amendment. Once firefighters are inside a building, they may remain there for the duration of the emergency. While there, the government may investigate the cause of the fire and may seize evidence of arson that is in plain view. In this case, no Fourth Amendment violation occurred by the firefighters’ entry to extinguish the fire at the defendant’s store, nor by the chief’s removal of the plastic containers. Similarly, no warrant was required for the re-entries into the building and for the seizure of evidence after the departure of the fire chief and other personnel since these were a continuation of the first entry that was temporarily interrupted by smoke.

However, if investigating officials require further access after the emergency concludes, they must obtain a warrant. To secure a warrant to investigate the cause of a fire, an official must show more than the bare fact that a fire has occurred. The government must establish probable cause that arson was committed. As this was not done for the non-emergency entries, they were considered unreasonable under the Fourth Amendment.