The Court found that a man, who placed his arm over his neighbour's fence, had been bitten by his neighbour's dog by reason of an act of trespass which served as an adequate defence for the offence of dog attack.
The judgment indicates that -
Robert Stanley Ellis lived next door to Christopher John Gerald Buchanan in Oak Park. Their properties were separated along the side boundary at the front by a chest-high fence. Mr Buchanan kept a non-dangerous dog in his secure front yard. The dog was too small for its snout or paws to reach the top of that fence.
One day Mr Ellis was talking to his son in the driveway of his home. He leaned on and allowed his arm partially to protrude over the fence. As the arm went down, it was bitten by the dog, causing Mr Ellis serious injuries.
Glenn Johnson is an authorised prosecution officer with the Moreland City Council. He charged Mr Buchanan, as the owner of the dog, with a dog attack offence under the Domestic Animals Act 1994 (Vic) s 29(4). That the victim was trespassing is a defence.
The charge was heard in the Magistrates’ Court of Victoria at Broadmeadows. Mr Buchanan admitted owning the dog, the bite to Mr Ellis and the serious injury which it caused. He relied on the defence that the bite occurred because Mr Ellis was trespassing on his premises by allowing his arm partially to protrude over the fence. The magistrate upheld that defence and dismissed the charge.
In this application for judicial review, Mr Johnson contends the magistrate erred in law on the face of the record by dismissing the charge when there was no or only a technical trespass.The magistrate noted Simpson v Bannerman  HCA 43; (1932) 47 CLR 378 but dismissed the charge on the ground that the incident occurred because the victim was trespassing on the defendant’s premises and therefore the defence in s 29(9)(b) applied.
I am satisfied also that [Mr] Ellis’s actions at law can constitute a trespass if he intruded or encroached into the property and space occupied by this dog.
I am satisfied that Mr Ellis did in fact invade the dog’s space, given (a) his testimony that his arm partially went over the fence and, secondly, independently, independent evidence given by Thompson on behalf of the prosecution who conducted his own test in relation to this dog and his evidence about where the dog’s paws and snout could reach or could not reach.
In those circumstances the defence provided by subsection (9) of section 29 under this particular Act is open to the defence.The dog was not proved to have a propensity to bite. the magistrate distinguished Simpson on the ground that it was a civil and not a criminal case.
The Supreme Court referred to Rigg v Alietti  WAR 203, Wilkins v Manning 13 WN (NSW) 220 and Trethowan v Capron  VicRp 73;  VR 460.
Bell J commented that the provisions of Part 3 of the Dangerous Animals Act 1994 (Vic) -
balance the rights of dog (and cat) owners with the rights to personal security and quiet enjoyment of the general community. The private right to own and keep dogs (including guard dogs) is not disturbed but is made subject to provisions relating to the control of dangerous dogs (div 3), menacing dogs (div 3A), restricted breed dogs (div 3B) and the powers and duties of local councils (div 4). Dogs on private property without permission are liable to be seized (s 23(1)). To allow a dog to be at large (s 24(1) and (2)) or in a place prohibited by a local council (s 26(1)) is an offence. So is keeping a dog that is, or allowing one to be, a nuisance (s 32(1)). It is in this regulatory and protective context that the legislation, in that part, has provisions for criminal offences and civil liability in relation to dog attack (s 29).
Section 29 makes provision for situations in a descending hierarchy of seriousness. By s 29(1) and (2), the person in apparent control or the owner of a dangerous dog which attacks or bites a person is guilty of an offence punishable by imprisonment or heavy fine, unless it is a guard dog guarding non-residential premises. By s 29(3) and (4), where a non-dangerous dog attacks or bites a person causing serious injury, the same persons are guilty of an offence punishable by moderate fine or, by s 29(5) and (6), by lesser fine if the injury is not serious. By s 29(7) and (8), the same persons are guilty of an offence punishable by lesser fine again where the dog rushes or chases any person.
... s 29(9)(b) creates a defence where ‘the incident occurred because ... a person was trespassing on the premises on which the dog was kept’. The defence is available in respect of all the offences specified in s 29. As the defence applies if the incident occurred ‘because’ of the circumstances specified in s 29(a)-(d), there must be a causal relationship between those circumstances and the attack or other criminalised conduct.
... 29(11) gives the court a power to award compensation for any damage caused by the conduct of the dog where the person is found guilty of an offence. The power is enlivened by a finding of guilt; it is therefore not necessary for the person to be convicted or penalised. The provision does not create a general cause of action to obtain compensation for damage caused by dog attack or confer a power on the court to award compensation in proceedings generally. As the power to award compensation is confined to cases where the person has been found guilty of an offence, it does not apply where the person is found not guilty by reason of the trespassing defence.Bell J went on to find that -
In my view, the magistrate did not err in law in dismissing the charge against the defendant on the basis of the trespass defence in s 29(9)(b) of the Domestic Animals Act. His Honour did not err in interpreting and applying that provision.
On the unchallenged findings which the magistrate made, the victim allowed his arm to go over the chest-high dividing fence and down into the defendant’s premises when he was leaning on that fence. The victim’s action was casual and inadvertent, but it was conscious and voluntary. The incursion was very minor, but even minor physical incursions into someone else’s property amount to trespass, unless authorised. It was not contended the victim had express or implied permission to do what he did. The incursion was into the defendant’s airspace, but that too is a trespass. The incursion of the victim’s arm into the defendant’s premises did not cause the defendant any damage, but damage is not an element of the tort of negligence. Applying the common law principles which govern the situation, the magistrate did not err in deciding that the victim had trespassed on the defendant’s premises.
Neither did the magistrate err in law in deciding that the victim was bitten because he was trespassing on the premises. The defendant kept the dog in the secure front yard of his home. On the found facts, the dog was too small to reach the top of the dividing fence with its snout or its paws. The defendant was bitten when he allowed his arm to go over and down into the defendant’s premises when he was leaning on the fence. On those facts and on the proper interpretation of the statutory provisions, the magistrate was entitled to find that there existed the necessary causal link between the bite and the trespass and to conclude that the charge must be dismissed because the defence applied.