Patent Litigation in Canada: 7 Essential Facts (2026)

A Canadian patent is only as strong as your willingness and ability to enforce it. Patent litigation in Canada looks familiar to US and European parties at first glance, then diverges in ways that decide cases: one court effectively owns validity nationwide, pre-trial injunctions are famously hard to win, and a successful patentee gets to choose between its own losses and the infringer’s profits. Knowing these rules before you sue — or before you are sued — is the difference between a strategy and a surprise.

Where Patent Litigation in Canada Happens

Canada has two possible forums, and the choice is not symmetric. The Federal Court has national jurisdiction over both infringement and validity, and only the Federal Court can declare a patent invalid in rem — meaning the ruling binds everyone, not just the parties, and the patent comes off the register. Its orders run across the whole country.

Provincial superior courts can hear infringement actions too, and can rule on validity as a defence, but only in personam — the decision binds the litigants alone and leaves the patent standing against the world. Because almost every serious dispute needs nationwide certainty, the overwhelming majority of patent litigation in Canada is run in the Federal Court. Patent law itself is federal, set out in the Patent Act (RSC 1985, c P-4).

The Presumption of Validity

Once CIPO grants a patent, section 43(2) of the Patent Act presumes it valid in the absence of evidence to the contrary. That presumption matters tactically: the party attacking the patent carries the burden of proving a ground of invalidity, and must do so on the civil standard.

It is a rebuttable presumption, not a shield. Canadian courts routinely invalidate claims, so a granted patent is a strong starting position rather than a guarantee. If you are the patentee, the presumption is yours to lose; if you are the defendant, it is the wall you have to get over.

How Invalidity Is Raised

A defendant sued for infringement almost always strikes back, raising invalidity by counterclaim or by a stand-alone impeachment action. The common grounds will be familiar: anticipation (lack of novelty) under section 28.2, obviousness under section 28.3, insufficient disclosure, overbreadth, and inutility.

The strategic point is jurisdictional. Only the Federal Court can give an in rem invalidity ruling, so a defendant who wants the patent destroyed for good — not merely neutralised in one dispute — litigates there. This is where disciplined prior-art work earns its keep, the same groundwork our invalidation team in Toronto prepares for accused parties. The mechanics of proving infringement itself mirror the analysis in our guide to patent infringement litigation.

Remedies: Damages or an Accounting of Profits

A successful patentee in Canada elects between two monetary remedies. Damages compensate for the patentee’s own losses — lost sales and a reasonable royalty on the rest. An accounting of profits instead strips the infringer of the profit it made from using the invention, regardless of what the patentee lost.

That election can be worth a fortune. In Nova Chemicals v Dow, the Supreme Court of Canada in 2022 upheld an accounting award of roughly CA$645 million — the largest reported patent award in Canadian history — on the logic that disgorgement removes the economic incentive to infringe. Patentees also get final injunctions as a matter of course once infringement is proven, plus reasonable compensation for the period between publication and grant.

• Damages — the patentee’s lost profits plus a reasonable royalty.
• Accounting of profits — the infringer’s profits, at the patentee’s election.
• Final injunction — ordinarily granted once infringement is established.
• Reasonable compensation — for infringement between publication and grant.

Why Injunctions Are Hard to Get Before Trial

Interlocutory (pre-trial) injunctions are rarely granted in Canadian patent cases. Courts apply the three-part RJR-MacDonald test: a serious issue to be tried, irreparable harm if the injunction is refused, and a balance of convenience favouring the applicant.

The irreparable-harm branch is usually fatal. Judges reason that money can compensate a patentee after trial, so the harm is not irreparable, and they decline to shut down a product before the merits are decided. The practical takeaway: do not build your enforcement plan around stopping a competitor overnight. Plan for a full trial and a final injunction instead.

Pharmaceuticals: The PM(NOC) 24-Month Stay

Drug patents follow a separate track. Under the Patented Medicines (Notice of Compliance) Regulations, when a generic manufacturer challenges a listed patent and the patentee responds by commencing an action, Health Canada is automatically barred from issuing the generic its marketing approval for up to 24 months while the case runs.

That automatic stay is a powerful contrast to ordinary infringement actions, where — as above — a pre-trial injunction is nearly impossible. For innovator pharma, the PM(NOC) regime is the real battleground, and it rewards getting the patent listing and the litigation timing exactly right.

How Canada Differs from US Patent Litigation

Parties used to US litigation should recalibrate on three points. There are no juries in the Federal Court — a single judge decides both infringement and validity, which tends to make outcomes more technically reasoned and less swayed by rhetoric. Discovery is narrower than US-style document production, so cases turn more on expert evidence than on a paper avalanche.

The third difference is cost risk. Canada follows the loser-pays principle: the unsuccessful party pays a portion of the winner’s costs, which can run into six or seven figures in a hard-fought case. That exposure disciplines both sides. A patentee with a thin claim thinks twice before suing, and a defendant with a weak invalidity theory thinks twice before fighting to trial. The result is a system that quietly pushes marginal cases toward settlement, while giving genuinely strong patents — and genuinely strong invalidity attacks — a clean, judge-driven forum to be decided in.

Timelines, Limitation Periods, and Appeals

A Federal Court patent action typically reaches trial in roughly two years, heard by a judge alone — there are no juries. No remedy is available for any act of infringement committed more than six years before the action starts, so sitting on a claim quietly erodes it.

Appeals go to the Federal Court of Appeal as of right, and from there to the Supreme Court of Canada only with leave, which is granted sparingly. Costs generally follow the event — the losing side pays a portion of the winner’s legal costs — which sharpens the incentive to settle strong or weak cases early. If you are weighing Canadian enforcement against the US, compare our overview of patent litigation in the United States and the filing groundwork in how to file a patent in Canada.

How PerspireIP Can Help

Whether you are enforcing a Canadian patent or defending against one, the case is usually won in the evidence gathered long before trial. PerspireIP supports Federal Court litigants with invalidity and prior-art searches, infringement and claim-chart analysis, and expert-grade technical work across our Canada practice, from Toronto to Ottawa. Contact us to scope the search and analysis behind your case.

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