It is difficult to arrive at a valid distinction between false arrest and false imprisonment. The two causes of action are practically indistinguishable. When there is a false arrest there is a false imprisonment, but in a false arrest detention is based on asserted legal authority to enforce the processes of the law. A false imprisonment can arise between private persons for a private end with no relevance to the administration of criminal law. Our primary concern here, of course, is solely with a detention under color of law. This article purports to describe the various situations in which an officer of the law can expose himself to liability for false imprisonment.
John M. Manos, Police Liability for False Arrest or Imprisonment, 16 Clev.-Marshall L. Rev. 415 (1967)