What is the burden of proving a search and seizure without a warrant?

substance (count 5) and driving under the influence of a controlled substance (count 7)). (See People v. Williams (1999) 20 Cal.4th 119, 130 [a defendant meets her initial burden of challenging the constitutionality of a warrantless search or seizure by "simply assert[ing] the absence of a warrant and mak[ing] a prima facie showing to support that assertion"; the prosecution then bears the burden of proving that the search or seizure was constitutionally reasonable].)