Malicious prosecution refers to a wrongful and groundless criminal or civil action brought against the plaintiff. An action for malicious prosecution can be brought against the underlying case's plaintiff, plaintiff's counsel and/or advisors. Liability for malicious prosecution may lie with the prosecutor or an informant, when the proceedings are malicious. However, grand jurors are not liable to an action for a malicious prosecution. The plaintiff must prove malice and want of probable cause, and the prosecution must result in his acquittal or a final judgment in his favor in a civil action.
Malicious prosection tort law seeks to protect against unjustifiable and unreasonable litigation. It requires a showing that the action was brought to harm the defendant or another improper motive. Malice is generally a wrongful intent, typically based in dislike of or animosity toward a person. This may be shown by, among others, sloppy legal or factual research, disparaging comments about the original defendant, a great imbalance in power between the parties, or an apparent desire by the original plaintiff to intimidate or punish the original defendant. The existence of probable cause is a complete defense to a claim for malicious prosecution. "Probable cause" is satisfied if any reasonable attorney would have thought the claim capable of prevailing.