The investigation concerned tow trucks, under the Transport Act 1983 (now the Transport (Compliance and Miscellaneous) Act 1983) and Transport (Tow Truck) Regulations 2005. (They're now replaced by the Accident Towing Services Act 2007 and Accident Towing Services Regulations 2008.)
Two VicRoads officers went to various business premises to enquire about a tow truck owned by Spectacular Views Pty Ltd. Nicolas Ectoros was a director of that company. The VicRoads officers finished at a business in Noble Park, and spoke with Mr Ectoros, who was also a director of the company listed on the door, Ultra Finish Accident Repair Centre (Dandenong) Pty Ltd.
Apparently the discussion didn't go smoothly, and Mr Ectoros told the VicRoads officers to get out. They stayed. Ultimately, Mr Ectoros and Spectacular Views were charged with various offences, including ones of not providing documents as required contrary to the legislative provisions in force at the time.
The Magistrates' Court dismissed the charges, concluding that at the time the demand was made for the documents, the VicRoads officers' implied licence to enter and remain was revoked and so they were trespassing. Consequently, they weren't acting in the lawful execution of their duty, and any evidence obtained after that was excluded.
VicRoads appealed. And lost.
The Supreme Court considered the High Court's decisions on implied licences to enter and remain on property.
The fundamental proposition is that entry to private property is a trespass unless authorised or excused.
A police officer who enters or remains on private property without the leave and licence of the person in possession or entitled to possession commits a trespass and acts outside the course of his duty unless his entering or remaining on the premises is authorized or excused by law: Halliday v Nevill (1984) 155 CLR 1 at 10 per Brennan J.
The Supreme Court discussed this and its effect on the appeal.
 In Plenty v Dillon the High Court approved what had been said by Brennan J in Halliday v Nevill in respect of the principle that every invasion of private property is a trespass, namely:The principle applies alike to officers of government and to private persons. A police officer who enters or remains on private property without the leave and licence of the person in possession or entitled to possession commits a trespass and acts outside the course of his duty unless his entering or remaining on the premises is authorised or excused by law.
 However, while the question whether an occupier of land has granted a licence to another to enter upon it is essentially a question of fact:..there are circumstances in which such a licence will, as a matter of law, be implied unless there is something additional in the objective facts which is capable of founding a conclusion that any such implied or tacit licence was negated or was revoked.
 Commonly a licence will be implied from the means of access to premises, for example where there is an unobstructed driveway or path leading to an entrance to private premises, without any notice forbidding entry. In those circumstances the law implies a licence to any member of the public to go to the entrance for any lawful purpose. But:..[s]uch an implied or tacit licence can be precluded or at any time revoked by express or implied refusal or withdrawal of it.
 In the present case it is not disputed that the officers had a tacit or implied licence to be on the premises. They were business premises with an unobstructed means of access and with an open door permitting members of the public to enter a front office for a lawful purpose.
 What is in dispute is whether that implied licence was effectively revoked.
It seems there was no direct evidence on the point, but the Court concluded there was enough to infer Mr Ectoros had authority to exclude other people from the property. The main case that deals with this is Coco v The Queen:
Every unauthorized entry upon private property is a trespass, the right of a person in possession or entitled to possession of premises to exclude others from those premises being a fundamental common law right. In accordance with that principle, a police officer who enters or remains on private property without the leave or licence of the person in possession or entitled to possession commits a trespass unless the entry or presence on the premises is authorized or excused by law. Statutory authority to engage in what otherwise would be tortious conduct must be clearly expressed in unmistakable and unambiguous language. Indeed, it has been said that the presumption is that, in the absence of express provision to the contrary, the legislature did not intend to authorize what would otherwise have been tortious conduct: Coco v The Queen (1994) 179 CLR 427 at 435 (citations excluded).
In Victoria, a mere occupier may require a person to leave a private place: Summary Offences Act 1966 s 9(1)(f). The common law appears to alo provide that right to any occupier: Cowell v Rosehill Racecourse Co Limited (1937) 56 CLR 605 at 631. And any person who enters or remains property must prove that it was done with the consent of the occupier or in accordance with some other lawful authority: Kuru v NSW (2008) 236 CLR 1 at .
Trespass by law enforcers might also interfere with rights under the Charter, specifically s 13 (right to privacy), 20 (property rights) and 21 (right to liberty and security of the person).
In this case, the Court accepted that Mr Ectoros had revoked the VicRoads officers' implied licence to remain on the property. That meant they were trespassers when they demanded various information from him. The Magistrates' Court decision to exclude any subsequent evidence — presumably under Evidence Act s 138 — wasn't challenged on the appeal.
The Supreme Court also went on to consider the authority delegated to the individual officers, and suggested it was probably lacking for the specific offences under investigation, but didn't finally decide this: at .
One area where I can see this decision becoming significant is those cases where police enter private premises and remain there until they complete their investigation. A classic scenario is when the police purport to establish a crime scene on private property and exclude people from the area. Unlike other States, Victoria presently doesn't have crime scene legislation such as Police Powers and Responsibilities Act 2000 (Qld) s 168 and Law Enforcement (Powers and Responsibilities) Act 2002 (NSW) s 95.
In the UK, the Court of Appeal suggested police could presume a landowner's consent to establish a crime scene — but didn't finally rule on the point in DPP v Morrison  Crim LR 727. But in any event, that was in a public right of way on private land (a shopping mall). The Court did not decide the police could establish a crime scene on private land with no right of entry for or use by the public — such as in a residence.
I reckon this case probably won't be appealed, because the Accident Towing Services Act 2007 contains express powers of entry, search and seizure that didn't exist in the old legislative scheme. The precedent effect of this decision is overcome by those changes.
But, the fundamental question about the scope and limits of entry to private property by law enforcement officials, how long they can remain and the consequence if they do when told to leave — especially when they purportedly establish a crime scene — remains ripe for litigation.