A patent holder in Canada has the exclusive right, privilege and liberty to making, constructing, using and selling the invention for the term of the patent, from the time the patent is granted., Patent Act, RSC 1985, c P-4, s 42. Any person who does any of these acts in relation to an invention without permission of the patent owner is liable for patent infringement.

When faced with an action for patent infringement, the defendant has a number of defences that they can use. These roughly fall into three categories: Non-infringement, asserting that the defendant does not make, use or sell the patented invention; Invalidity, asserting that the patent should not have been granted in view of prior art; Defences based on user rights, statutory or otherwise.

Remedies in Canadian patent law generally track both common law and equitable remedies. Equitable remedies include injunctions (both final and interlocutory) and an accounting of profits. Common law remedies include damages aimed at putting the plaintiff in the position he would have occupied had the infringement not occurred.

Invalidity defences

In order to obtain a patent, an invention must be: Allowable subject matter; New; Useful; Not obvious to a person skilled in the art., Patent Act, RSC 1985, c P-4, ss 2, 28.2, 28.3.

The Canadian Patent Act allows that:

Therefore, if a person can show that a patent claims improper subject matter, is anticipated, inoperable or obvious, then the patent can be declared void. For example, if a defendant can show evidence that the claimed invention was known as of the claim date, and thus the invention is not new, the patent can be declared void.

Improper subject matter

Under section 2 of the Patent Act, an invention is defined as:

If the defendant can successfully show that the invention does not fall into any of these classes, then the patent will be invalid. There are a few cases where this has occurred, such as Harvard College v. Canada (Commissioner of Patents).Harvard College v. Canada (Commissioner of Patents), 2002 SCC 76 (Supreme Court of Canada) In that case, it was held that while the genetically engineered plasmid and transgenic mouse cells were the proper subject of a patent, the genetically modified mouse and other higher life forms were not.

Lack of utility or inoperability

In applying for a patent, the applicant must show that the patent is operable as of the claim date. The claim itself must specify the invention in enough detail that a person skilled in the art would be able to reproduce the invention.X v. Commissioner of Patents, (1981) 59 CPR (2d) 7 (Federal Court), Minerals Separation North American Corp. v. Noranda Mines Ltd., (1952) 15 CPR 133 (Judicial Committee of the Privy Council), Burton Parsons Chemicals, Inc. v. Hewlett-Packard (Canada) Ltd. 1 SCR 555 (Supreme Court of Canada) In lieu of an operable invention, the applicant must show that there is a sound factual basis for the invention and explain why the invention should work.Apotex Inc. v. Wellcome Foundation Ltd., 2002 SCC 77 (Supreme Court of Canada)

This defence was successfully used in Minerals Separation North American Corp. v. Noranda Mines Ltd., where a mining company sued another for the use of a patented process using a xanthate frothing flotation method in order to separate minerals from ore. It failed because the patent claims included all xanthates, but it was known that not all xanthates could be used in the process. Consequently, the patent was held invalid as a person skilled in the art could not use the patent specifications in order to reproduce the effect and the patent was inoperable.Minerals Separation North American Corp. v. Noranda Mines Ltd., (1952) 15 CPR 133 (Judicial Committee of the Privy Council) However, in Burton Parsons Chemicals, Inc. v. Hewlett-Packard (Canada) Ltd., the same defence was not successful because a person skilled in the art would know which of the unspecified material could and could not be used.Burton Parsons Chemicals, Inc. v. Hewlett-Packard (Canada) Ltd. 1 SCR 555 (Supreme Court of Canada)

Anticipation

An anticipation defence attempts to show that the invention was not new as of the claim date. The current test used in Canadian Patent law was enunciated in Apotex Inc. v. Sanofi‑Synthelabo Canada Inc. The test includes two prongs: prior disclosure and enablement.

The prior disclosure requirement asks whether a person skilled in the art would know that the previous disclosure covered the same material as the patent at issue. There is no trial and error permitted at this stage of the inquiry - either doing what is specified in the earlier disclosure or patent would infringe the patent at issue, or it will not.

The enablement requirement asks whether a person skilled in the art would be able to work the invention as disclosed in the prior art. Some experimentation is allowed at this stage of the inquiry, but the experimentation must not pose an undue burden. Long and arduous experimentation, for example, would indicate that the prior disclosure did not include enough information for a defence of anticipation to succeed.

The earlier case Reeves Brothers Inc. v. Toronto Quilting & Embroidery Ltd.Reeves Brothers Inc. v. Toronto Quilting & Embroidery Ltd., (1978) 43 CPR (2d) 145 (Federal Court) holds that the prior disclosure must include all requisite factors in a single document without making a mosaic. In Canadian patent law, there is a high bar for a test of anticipation to succeed.

Obviousness

An obviousness defence attempts to show that the invention is an obvious or logical next step of a previously disclosed invention. In order for the defence to succeed, it must be shown that a person skilled in the art would be able to take this particular step in innovation. Beloit Canada Ltd. et al. v. Valmet Oy defines the person skilled in the art as a: "technician skilled in the art but having no scintilla of inventiveness or imagination; a paragon of deduction and dexterity, wholly devoid of intuition; a triumph of the left hemisphere over the right. The question to be asked is whether this mythical creature [...] would, in the light of the state of the art and of common general knowledge as at the claimed date of invention, have come directly and without difficulty to the solution taught by the patent".Beloit Canada Ltd. et al. v. Valmet Oy (1986) 8 CPR (3d) 289 (Federal Court of Appeal)

The current approach used in Canadian patent law was enunciated by the Supreme Court of Canada in Apotex Inc. v. Sanofi‑Synthelabo Canada Inc. In coming to its decision, a court must consider: The notional person skilled in the art and that person's relevant common knowledge; The inventive concept of the claim must be determined and construed; Any differences that exist between the art prior to the claim and the inventive concept of the claim; Whether these differences constitute steps which would be obvious to the person skilled in the art, without knowledge of the invention.

In some fields, experimentation is common and some experiments are considered to be "obvious-to-try". Apotex Inc. v. Sanofi‑Synthelabo Canada Inc. outlines major considerations in fields where this occurs: whether it is self-evident that what is being tried should work, the extent of the effort required to achieve the invention, and motive in the prior art to find a solution to the problem. In some cases, this could lead to a finding that the additional step taken was obvious and therefore the patent for the additional innovation will be considered void.

Non-infringement defences

A defendant in a patent infringement case can also argue that while the plaintiff's patent is valid, they have not infringed the patent. Under section 42 of the Canadian Patent Act, a patent holder has the exclusive right, liberty and privilege to make, construct, sell and use the invention for the duration of the patent. A defence based on these terms would typically focuses on use, which has been given special attention due to the difficulty of interpreting the term "use".

Use has been defined in Monsanto Canada Inc. v. Schmeiser as any activity that deprives an inventor, in whole or in part, directly or indirectly, of full enjoyment of the monopoly as conferred by law. Monsanto Canada Inc. v. Schmeiser, 2004 SCC 34 (CanLII), 1 SCR 902 (Supreme Court of Canada), para 35 Monsanto Canada Inc. v. Schmeiser sets a very high bar for a defence based on these terms, as possession of the invention leads to an rebuttable presumption of use. The presumption can be rebutted if the defendant can show that they genuinely did not intend on using the patented invention. Monsanto Canada Inc. v. Schmeiser, 2004 SCC 34 (CanLII), 1 SCR 902 (Supreme Court of Canada), para 58 For example, in British United Shoe Ministry v. Simon Collier Ltd., the patented invention was a part of a machine which the defendant bootmaker had removed and set aside. It was possible to run the machine without using the patented part, and the defendants willingly returned the patented invention when action was commenced.British United Shoe Machinery Co. v. Simon Collier Ltd. (1910), 27 RPC 567, p 571; Monsanto Canada Inc. v. Schmeiser, 2004 SCC 34 (CanLII), 1 SCR 902 (Supreme Court of Canada), para 54.

If the patented invention occurred as an intermediary of a process or the patented process occurred outside of Canada, patent infringement may still be found.Pfizer v. Canada (Health), 2007 FC 989 (CanLII) (Federal Court) A court should consider the following factors in determining whether there has been infringement in these cases:Pfizer v. Canada (Health), 2007 FC 989 (CanLII) para 90 (Federal Court) The importance of the process or intermediary to the final product sold in Canada; Whether the final product contains all or part of the patented product; The stage at which the patented product or process is used; The number of instances of use made of the patented process or object; The strength of the evidence indicating that if the process or intermediary had occurred in Canada, the product or process would constitute infringement.

In a case of secondary infringement or inducement, the plaintiff patent holder would need to show:MacLennan v. Produits Gilbert Inc., 2008 FCA 35 (CanLII) para 13 (Federal Court of Appeal) Primary infringement from the direct infringer; Influence from the seller to engage in infringement, to the point where without the influence there would have been no infringement; The influence was knowingly exercised by the seller. A successful defence could be based on any of these grounds in the case of secondary infringement or inducement.

Gillette defence The Gillette defence is a way of arguing non-infringement by proving invalidity without requiring the patent claims to be construed. The defence is based on an early 1900s decision from the House of Lords and allows the defendant to plead that their alleged infringing actions are part of the prior art, and thus either the patent is invalid for claiming the prior art or if the patent is valid, the defendant does not infringe.Gillette Safety Razor Company v. Anglo-American Trading Company Ltd. 30 R.P.C. 465 (H.L.) In view of the Supreme Court's decision in Free World Trust, any Gillette Defence would still require that the patent claims are construed prior to determining infringement.

User rights

International treaties such as NAFTA North American Free Trade Agreement, 17 December 1992 (Ottawa: Supply and Services, 1993) art. 1709(6) and TRIPsAgreement on Trade-Related Aspects of Intellectual Property Rights, Including Trade in Counterfeit Goods (1994), 25 IIC 209, art. 30 allow member states to create exceptions from the exclusive rights enjoyed by patent owners where the exceptions: do not unreasonably conflict with the normal exploitation of a patent; do not unreasonably prejudice the legitimate interests of the patent owner;