Excessive force used in making an arrest: does it make the arrest ipso facto unlawful?

The purpose of this article is to consider whether or not the use of excessive force in effecting an arrest makes the arrest ipso facto unlawful at common law. With a dearth of appellate court authority on point in either Australia or the United Kingdom, the question is presently open. It is my argument that as force is not a minimum condition of an arrest, its excessive use will not, therefore, make unlawful an otherwise lawful arrest. This conclusion is a matter of some import. It exposes an arrester to civil and possibly even criminal liability for assault but not to an action for false imprisonment. It may also have practical repercussions for the possible discretionary exclusion of evidence on public policy grounds. In theory, it should not matter whether excessive force made an arrest unlawful or not, for the public policy discretion permits a judge to exclude evidence illegally or improperly obtained. But common sense suggests that a judge may not be so likely to exclude evidence when the relevant conduct amounts only to police impropriety not illegality.