What is the test for a search warrantless search?

Defendant challenges the warrantless search on two grounds. First, he argues the search was unconstitutional because the police used excessive [208 Cal.App.3d 1336] force. Second, he asserts the search was unjustified because there were no exigent circumstances. In reviewing a challenged search or seizure, we must uphold the trial court's factual findings if those findings are supported by substantial evidence (People v. Siripongs (1988) 45 Cal.3d 548, 566-567, 247 Cal.Rptr. 729, 754 P.2d 1306), but we are required to exercise our independent judgment when measuring those facts against the constitutional standard of reasonableness. (People v. Williams (1988) 45 Cal.3d 1268, 1301, 248 Cal.Rptr. 834, 756 P.2d 221.)