Qualified immunity shields government officials performing discretionary functions from damages liability unless their conduct violated a constitutional right that was clearly established at the time.
Two questions. Whether the facts show a violation, and whether the right was clearly established. Courts may address them in either order, which means a case can be dismissed without any ruling on whether a violation occurred.
Clearly established requires that existing precedent placed the question beyond debate — defined with a high degree of specificity rather than at a general level. A general proposition that excessive force is unlawful does not answer whether a particular use of force was.
Which precedent counts. Controlling authority in the jurisdiction, and in some circumstances a consensus of persuasive authority. A single out-of-circuit decision usually does not suffice.
The obvious case. Where conduct is so plainly unlawful that no prior case is needed, immunity is unavailable, but courts invoke this sparingly.
Procedure. It is an immunity from suit, not merely from liability, and is raised early — on the pleadings, then again at summary judgment. Denials are immediately appealable on the legal question, which shapes the timeline of civil rights litigation.
Not available to municipalities, nor to private parties in most circumstances.