How is the federal district court's ruling on a motion to suppress evidence reviewed de novo?

The district court's ruling on a motion to suppress evidence is reviewed de novo. United States v. Chaudhry, 424 F.3d 1051, 1052 (9th Cir.2005). "Factual determinations underlying the district court's ruling are reviewed for clear error." Id.

We have not addressed which party bears the burdens of production and persuasion in a motion to suppress evidence found during a border search, although, generally,"[t]he government bears the burden of justifying a warrantless search." United States v. Johnson, 936 F.2d 1082, 1084 (9th Cir.1991) (per curiam).