Patent Opposition and Estoppel in Australia: Lessons from Orikan v VMS

Two Federal Court decisions arising from the same patent dispute over parking-sensor technology have clarified some important — and previously uncertain — questions about the relationship between patent opposition proceedings and later infringement litigation in Australia. The cases are Orikan Group Pty Ltd v Vehicle Monitoring Systems Pty Limited [2023] FCA 1031 and Orikan Group Pty Ltd v Vehicle Monitoring Systems Pty Limited (No 2) [2026] FCA 407.

The practical lessons are significant for both patent owners contemplating enforcement and for businesses that have opposed a patent and later find themselves on the wrong end of an infringement claim.

Background: Parking Sensors and a Long-Running Fight

The patent at the centre of the dispute is Australian Patent No. 2013213708, entitled "Vehicle Detection." The invention covers vehicle detection units (VDUs) embedded beneath parking spaces that use magnetic sensors to determine when a vehicle has arrived, departed, or overstayed its permitted time. The VDU processes the sensor data locally and wirelessly transmits a notification to a supervisory device — such as a parking officer's handheld terminal — in a format ready for direct entry into infringement-issuing software.

Orikan Group (and its predecessors) alleged that Vehicle Monitoring Systems Pty Limited (VMS) infringed the patent by operating its Parking Overstay Detection System (PODS). VMS denied infringement, cross-claimed for revocation of the patent, and also ran a prior use defence — arguing that the patent was only entitled to a priority date of 7 August 2013, by which time VMS had already been using its own system in the market.

The dispute had a prior history: VMS had previously contested the grant of the patent in opposition proceedings before the Federal Court (then involving Orikan's predecessor, SARB Management Group): Vehicle Monitoring Systems Pty Ltd v SARB Management Group Pty Ltd [2020] FCA 408. Those proceedings produced findings on claim construction and on some validity grounds — and it was the carry-over effect of those earlier findings into the later infringement case that gave rise to several of the most interesting legal questions.

The 2023 Interlocutory Decision: Can Old Opponents Raise New Grounds?

Before the infringement trial, Orikan applied to have several of VMS's invalidity grounds struck out. Orikan's argument was essentially that VMS — having participated in the earlier opposition proceedings — should have raised all available grounds at that stage, and was now estopped or otherwise precluded from running new grounds in the infringement proceeding.

The Court rejected that application. His Honour found that VMS had acted reasonably in confining its validity challenge during the opposition, given the different character and relatively lower stakes of those proceedings. Crucially, the factual bases for the new grounds differed from those previously litigated, so there was no real risk of inconsistent findings across the two sets of proceedings. The Court also found it was not likely that allowing the grounds in the infringement proceeding would increase the overall costs of resolving the dispute.

Following this decision, VMS amended its cross-claim and added a ground of lack of sufficiency — a ground that, as it turned out, would prove decisive at trial.

The 2026 Trial Decision: Patent Invalid, Infringement Not Established

At trial, the Court found in VMS's favour on almost every front.

Orikan failed to establish infringement. The Court also found that none of the asserted claims were entitled to a priority date earlier than 7 August 2013. That finding directly enabled VMS's prior use defence to succeed.

On the cross-claim, claims 1 to 24 of the patent were found invalid on two independent grounds.

Lack of Sufficiency

Orikan argued that VMS was estopped from raising insufficiency at all, pointing to the fact that the ground had been litigated in the earlier opposition and decided against VMS at that stage.

The Court applied the established principle from Blair v Curran (1939) 62 CLR 464: issue estoppel operates only in respect of matters that were necessarily established as the legal foundation of the earlier judgment. Because VMS was advancing a different factual basis for insufficiency — the earlier proceeding had found the patent sufficient as to feature A; VMS now argued it was insufficient as to a different feature B — the estoppel did not apply. The new argument could proceed.

On the merits, the Court accepted VMS's expert evidence that implementing the vehicle detection and violation determination step to the level of accuracy required by the patent would demand a degree of ingenuity beyond what could reasonably be expected of a person skilled in the art. The patent's specification was therefore insufficient.

The insufficiency finding had a further consequence: because the corresponding provisional, PCT, and parent applications contained substantially the same inadequate disclosure, the patent could not claim an earlier priority date. The 7 August 2013 date stood — and VMS's prior use defence with it.

Best Method

The patent was also found invalid for failure to disclose the best method of performing the invention. Applying the Full Court's recent decision in NOCO Company v Brown and Watson International Pty Ltd [2026] FCAFC 44, the relevant date for assessing the patentee's knowledge of the best method is the filing date of the complete specification in suit — here, 7 August 2013. Internal Orikan specifications that predated that date disclosed a best method that had not been included in the patent specification. The ground was therefore made out.

What Binds the Parties — And What Doesn't

The Court confirmed that both Orikan and VMS were bound by the claim construction findings made in the earlier opposition proceedings, to the extent those findings were legally indispensable to the earlier decision. Even construction findings that were not strictly essential to the earlier outcome are likely to be followed in subsequent proceedings, unless they are shown to be clearly wrong. Parties cannot relitigate how claims are interpreted simply because they are in a new forum or because the stakes are higher.

That is in contrast to invalidity grounds, where a different factual basis can open the door — at least where the new argument arises in the context of defending an infringement claim by cross-claim for revocation. The Court noted that the position might be different where a party seeks to initiate a revocation proceeding against the patentee independently, rather than raising invalidity as a cross-claim in response to being sued.

Key Takeaways

These decisions — together spanning three years of litigation from interlocutory skirmishing to a full trial — have practical consequences for anyone involved in Australian patent disputes:

• Opposition proceedings are not the final word on validity. A party that opposed a patent and lost (or succeeded only in part) may still be able to challenge validity on additional grounds if sued for infringement, provided those grounds rest on a genuinely different factual foundation. Prior opposition involvement does not automatically foreclose later invalidity arguments in the infringement context.

• Claim construction findings travel with the parties. Whatever the Federal Court decides about how claims are to be read in an opposition, those findings bind the same parties in subsequent proceedings. This makes it critical to put your best claim construction arguments forward in opposition — not to hold them back for a later round.

• Sufficiency deserves careful attention on multiple fronts. The outcome here illustrates that insufficiency can be run on a narrower or broader basis without the earlier finding closing off the later one, provided the factual underpinning genuinely differs. This gives challengers some flexibility — but also reinforces for patentees that their specification must be robust across all the technical ground the claims are intended to cover.

• Best method is assessed at the complete specification filing date. Following NOCO v Brown and Watson, patentees and their attorneys need to ensure that all known best methods are disclosed in the complete specification as filed. Internal documents — R&D records, technical specifications, engineering notes — may later surface in litigation to demonstrate that a better method was known but not disclosed.

• Prior use defences hinge on priority. Disputes about the correct priority date can be case-determinative. If the sufficiency of an earlier application is in doubt, a patent owner's ability to assert an early priority date may be vulnerable — which can expose the entire enforcement position to a prior use challenge.

How Stellar IP Law Can Help

Whether you are defending a patent through opposition proceedings, responding to an infringement claim, or building a patent portfolio that will withstand litigation scrutiny, Stellar IP Law can advise on the strategy that best protects your position. Contact us to discuss your matter.