Plenty v Dillon

The High Court of Australia considered an appeal from the Supreme Court of South Australia in a dispute between a landowner, Mr. Plenty, and a police officer, Detective Sergeant Dillon. The core of the disagreement concerned the legality of the police officer's entry onto Mr. Plenty's property without a warrant to serve a summons. Mr. Plenty had sought a declaration that the entry was unlawful and an injunction to restrain further trespass.

The central legal question before the High Court was whether a police officer, in the absence of a warrant or statutory authority, possessed an implied licence to enter private property for the purpose of serving a summons. This involved an examination of the common law rights of landowners to exclude others from their property and the extent to which those rights could be overridden by the duties of law enforcement.

The Court held that the common law does not grant police an implied licence to enter private property to serve a summons. The right of a landowner to privacy and to exclude others from their property is a fundamental common law right. While police have a duty to enforce the law, this duty does not, at common law, extend to authorising trespass for the purpose of serving civil process. The Court distinguished this situation from circumstances where police might enter to prevent a crime or arrest a suspect, which are grounded in different legal principles.

Consequently, the High Court found that Detective Sergeant Dillon's entry onto Mr. Plenty's property was unlawful. The appeal was dismissed, upholding the Supreme Court of South Australia's finding that the entry constituted a trespass.