What is qualified immunity for an arresting officer in a false arrest case?

Qualified immunity is a complete defense to false arrest claims. An arresting officer is entitled to qualified immunity even when, as in this case, probable cause to arrest does not exist, if he can establish that there was arguable probable cause to arrest. Escalera v. Lunn, 361 F.3d 737, 743 (2d Cir.2004).

Arguable probable cause exists if either (a) it was objectively reasonable for the officer to believe that probable cause existed, or (b) officers of reasonable competence could disagree on whether the probable cause test was met. Id. (internal quotation marks omitted). In this respect, the qualified immunity test is more favorable to the officers than the one for probable cause. Id. The test is not toothless, however: If officers of reasonable competence would have to agree that the information possessed by the officer at the time of arrest did not add up to probable cause, the fact that it came close does not immunize the officer. Jenkins v. City of New York, 478 F.3d 76, 87 (2d Cir.2007).