Malley v. Briggs

The Court noted that, as the qualified immunity defense has evolved, it provides ample protection to all but the plainly incompetent or those who knowingly violate the law. Thus, a defendant will not be immune if, on an objective basis, it is obvious that no reasonably competent officer would have concluded that a warrant should issue. However, if officers of reasonable competence could disagree on this issue, immunity should be granted.

Only where the warrant application is so lacking in indicia of probable cause as to render official belief in its existence unreasonable will the shield of immunity be lost. The appropriate question to be answered is such cases is: whether a reasonably well-trained officer in the defendant’s position would have known that his affidavit failed to establish probable cause and that he should not have applied for the warrant. It is reasonable to require the officer applying for the warrant to minimize this danger by exercising reasonable professional judgment.