False arrest  False arrest is a common law tort, where a plaintiff alleges they were held in custody without probable cause, or without an order issued by a court of competent jurisdiction. Although it is possible to sue law enforcement officials for false arrest, the usual defendants in such cases are private security firms. In the United Kingdom, a police officer may arrest a person under if they are executing a warrant, if they have a "reasonable belief" that someone is involved in a criminal offence, or if they have a reasonable belief that someone is about to be involved in a criminal offence "and" it is necessary to arrest that person. Proof of wrongful arrest depends on proving that an officer did not have a reasonable belief and that it was not necessary to arrest someone. Most cases where unlawful arrest was determined emerge from a claim that an arrest was unnecessary. The specific legislation governing, in England and Wales, the reasons for which a police officer may arrest a person are in section 24 of the Police and Criminal Evidence Act 1984. Damages for unlawful arrest depend primarily on the time in custody and can be aggravated if the police acted maliciously. After an arrest, if the charges are dropped, a person will sometimes file legal action or a complaint against the appropriate arresting agency. In most jurisdictions, the arrest powers of police and police agents are in excess of those afforded to ordinary citizens (see citizen's arrest). However, the powers of police officers to arrest are not unlimited. Generally speaking:   Most cases of false arrest involve accusations of shoplifting, and are brought against security guards and retail stores. A guard cannot arrest someone merely on the suspicion that person is going to commit a theft. In most jurisdictions, there must be some proof that a criminal act has "actually" been committed. For example, a guard does not have reasonable and probable cause if a shopper has not yet paid for merchandise they are carrying in the belief that the person intends to leave without making payment. Instead, there must be an actual act committedthe person "must" make an actual attempt to leave the store without paying for the merchandise. In the United States and other jurisdictions, police officers and other government officials are liable for clear deprivation of rights, but are partially shielded from false arrest lawsuits through the doctrine of qualified immunity, when such a violation qualifies as "not obvious," by a US Supreme Court test. This doctrine can protect officials from liability when engaged in legal grey areas including qualifying discretionary actions in the arrests of suspects. However, the officer's actions must still not violate "clearly established law," or this protection is void.