What is the test for a warrant to search a person's home without a warrant?

Although "'"searches and seizures inside a home without a warrant are presumptively unreasonable,"'" "the warrant requirement is subject to certain exceptions." (Brigham City, Utah v. Stuart (2006) 547 U.S. 398, 403 [126 S.Ct. 1943, 164 L.Ed.2d 650].) One such exigency allowing police to enter a home without a warrant exists "'when they have an objectively reasonable basis for believing that an occupant is

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seriously injured or imminently threatened with such injury.' [Citation.] "'The need to protect or preserve life or avoid serious injury is justification for what would be otherwise illegal absent an exigency or emergency.'" [Citation.] '"'There is no ready litmus test for determining whether such circumstances exist, and in each case the claim of an extraordinary situation must be measured by the facts known to the officers.'"' [Citation.] On appeal, we uphold the trial court's factual findings if they are supported by substantial evidence, but review independently its determination that the search did not violate the Fourth Amendment. [Citation.]" (People v. Troyer (2011) 51 Cal.4th 599, 605.)

"The "'emergency aid exception'" to the warrant requirement 'does not depend on the officers' subjective intent or the seriousness of any crime they are investigating when the emergency arises.' [Citation.] Rather, the exception 'requires only "an objectively reasonable basis for believing" [citation] that "a person within [the house] is in need of immediate aid."' [Citation.] 'We are to approach the Fourth Amendment . . . with at least some measure of pragmatism. If there is a grave public need for the police to take preventive action, the Constitution may impose limits, but it will not bar the way.' [Citation.]" (People v. Troyer, supra, 51 Cal.4th at pp. 605-606.)