A false arrest is one that is not within the confines of the law and not compliant with the necessities of a legal arrest, such as the giving of the Miranda warning. Holding someone against their will without the proper authority to do so is also considered false arrest and is a civil crime. The unlawful restraining of a person's physical body is considered false arrest.
The concept has become clarified since the advent of security guards in explaining the limits of their legal duties to restrain suspects in particular. In general, false arrest has been one of the earliest crimes on the books.