The Fourth Amendment of the federal Constitution requires state and federal courts to exclude evidence obtained from unreasonable government searches and seizures. (People v. Williams (1999) 20 Cal.4th 119, 125.) State and federal constitutional claims regarding the admissibility of evidence obtained by an allegedly improper search and seizure are reviewed under the same standard. (In re Tyrell J. (1994) 8 Cal.4th 68, 76, overruled on another ground in In re Jaime P. (2006) 40 Cal.4th 128; People v. Camacho (2000) 23 Cal.4th 824, 829-830.) A warrantless search is presumed to be illegal. (Mincey v. Arizona (1978) 437 U.S. 385, 390.) The prosecution always has the burden of justifying a warrantless search or seizure by proving that it fell within a recognized exception to the warrant requirement. (People v. Williams, at p. 130; In re Tyrell J., at p. 76.) The test for the existence of a show of coercive authority is an objective one, and does not take into account the perceptions of the particular person involved. (In re Manuel G., supra, 16 Cal.4th at p. 821; California v. Hodari D. (1991) 499 U.S. 621, 628.) As one court has noted, "it is not the nature of the question or request made by the authorities, but rather the manner or mode in which it is put to the citizen that guides us in deciding whether compliance was voluntary or not." (People v. Franklin (1987) 192 Cal.App.3d 935, 941.) "Where a motion to suppress is submitted to the superior court on the preliminary hearing transcript, the appellate court disregards the findings of the superior court and reviews the determination of the magistrate who ruled on the motion to suppress, drawing all presumptions in favor of the factual determinations of the magistrate, upholding the magistrate's express or implied findings if they are supported by substantial evidence, and measuring the facts as found by the trier against the constitutional standard of reasonableness." (People v. Thompson (1990) 221 Cal.App.3d 923, 940.)