The doctrine of qualified immunity is a judicially created affirmative defense
which protects public officials from being tried for violations of constitutional
rights. This defense to liability for constitutional claims operates in a similar
manner as the discretionary function exception to tort liability. Qualified
immunity applies to federal, state, and local officials equally. Butz v.
Economou, 438 U.S. 478 (1978). This immunity is designed to be immunity
from suit, not merely from a finding of liability. Mitchell v. Forsyth, 472 U.S. 511
(1985). The distinction is important because qualified immunity can be invoked
and the lawsuit dismissed on summary judgment without the suit going
through pretrial procedure and discovery. A pretrial motion is the vehicle for
invoking qualified immunity. If the lower court denies qualified immunity, a
defendant may appeal that ruling before litigation on the merits proceeds. This
allowance for interlocutory appeal may significantly delay the litigation.