Must impoundment be reasonable under the Fourth Amendment, or conducted pursuant to standardized procedures, or both?

QUESTION PRESENTED The warrantless impoundment of an arrested person’s car is permissible only when it is “totally divorced” from any investigation of criminal activity. Cady v. Dombrowski, 413 U.S. 433, 441 (1973). Impoundment may be undertaken only for the purpose of “public safety” or “community caretaking.” South Dakota v. Opperman, 428 U.S. 364, 368 (1976); Must impoundment be reasonable under the Fourth Amendment, as some circuit courts have held, or conducted pursuant to standardized procedures, as others have held, or both, as still others have held? Can law enforcement impound a vehicle at their discretion, unconstrained by any specific and reasonable standard operating procedures, where public safety or community caretaking needs are illusory at best? i