What is the test for obtaining a warrant to impound a vehicle without a warrant?

Generally, "[a] seizure conducted without a warrant is per se unreasonable under the Fourth Amendment subject only to a few specifically established and well-delineated exceptions." Id. at 1196 (quoting United States v. Hawkins , 249 F.3d 867, 872 (9th Cir. 2001) ). The parties do not dispute that neither the County nor City officials who impounded the plaintiffs' vehicles had warrants authorizing the impound, so we begin from the premise that the impounds were unreasonable. We then examine whether any "specifically established and well-delineated exceptions" to the warrant requirement apply that would make the impounds reasonable. See id.

The County argues that such an exception exists because we should categorically

[912 F.3d 516]