What is the test for qualified immunity for Fourth Amendment violations?

When a law enforcement officer asserts qualified immunity from liability for Fourth Amendment violations, the district court must determine whether, in light of clearly established principles governing the conduct in question, the officer objectively could have believed that his conduct was lawful. See Anderson v. Creighton, 483 U.S. 635, 641, 107 S.Ct. 3034, 3039, 97 L.Ed.2d 523 (1987). This standard requires a two-part analysis: 1) Was the law governing the official's conduct clearly established? 2) Under that law, could a reasonable officer have believed the conduct was lawful?