What is the test for warrantless entry under the Fourth Amendment?

The agents' warrantless entry securing the residence was a seizure subject to the requirements of the Fourth Amendment. United States v. Howard, 828 F.2d 552, 554 (9th Cir.1987). The government has the burden of justifying the seizure under one of a few specifically established exceptions to the warrant requirement. To justify a warrantless entry, the government must demonstrate both probable cause and the existence of an exception to the warrant requirement, such as exigent circumstances. Lindsey, 877 F.2d at 780. Because we find that there was no probable cause, we need not consider whether exigent circumstances existed.