Whether, absent an emergency, the Fourth Amendment permits the police to enter a home without a warrant based on an informant's signal that criminal activity is taking place inside. DECIDED
The police do not need a warrant to enter a home if they have consent from the homeowner. The question in this case is whether a homeowner who has allowed an undercover informant into his home has implicitly granted the police consent to enter the home as well. The ACLU's amicus brief argues that the so-called "consent-once-removed" doctrine should not be stretched to include unreliable and untrained informants. The ACLU brief also argues, on a second point, that courts should be required to decide whether government officials have acted unconstitutionally before deciding whether they are entitled to qualified immunity from damages because the law was not "clearly established" at the time.