Understanding the Gillette Defence in Patent Infringement Cases

When a company sues a competitor for patent infringement, the instinctive response is to argue “I didn’t copy you.” But there is a sharper, more strategic defence available – one that flips the entire dispute on its head. Instead of saying “I didn’t infringe your patent,” the defendant essentially says, “What I’m doing was already public knowledge long before your patent existed – so either your patent is invalid, or it simply doesn’t cover me.” This is the essence of the Gillette Defence, a concept born from British jurisprudence in 1913 that continues to shape patent litigation across common law jurisdictions, including India, over a century later.

The origin: a dispute over safety razors 🔗

The Gillette Defence takes its name from the landmark House of Lords decision in Gillette Safety Razor Co v Anglo-American Trading Co (1913). The case centred on King Camp Gillette’s safety razor – a design using a thin, flexible blade that, when clamped into the holder, bent into a gentle curve. This curvature was the heart of the invention; it gave the blade stiffness for shaving and allowed adjustability that earlier rigid blades lacked.

The defendant’s product, sold under the name “Duplex,” used a thin blade as well – but clamped it flat between two flat surfaces without any bending mechanism. The defendants argued that their design was based on an earlier American specification by one John Butler, which predated Gillette’s patent. Butler’s design had already described using a flat holder with a blade clamped transversely to a handle. The only real difference between Butler’s prior art and the Duplex razor was that the Duplex used a thinner blade. Lord Moulton, delivering the leading judgment, held that since the defendants’ flat holder did not use Gillette’s bending mechanism, it did not infringe the patent – and that Gillette’s claims, if read broadly enough to capture what the defendants were doing, would also sweep in prior art that already existed in the public domain.

The principle Lord Moulton articulated was direct and powerful: if a defendant is doing nothing more than what was already open to the public before the patent’s priority date, that defendant cannot be said to be infringing a valid patent.

The “squeeze”: how the defence actually works 🔗

The strategic genius of the Gillette Defence is that it creates an inescapable dilemma – often called a “squeeze” or Catch-22″ – for the patent holder. A successful Gillette Defence puts the patentee in a position where, whichever way the patent claims are interpreted, the patentee loses. Here is how:

First prong – broad interpretation: If the patent claims are read broadly enough to cover the defendant’s product or process, those same claims would also cover the prior art that existed before the patent’s priority date. A patent that claims something already known to the public is invalid for lack of novelty. So the patent falls.

Second prong – narrow interpretation: If the patent claims are read narrowly enough to sidestep the prior art (and thus preserve the patent’s validity), then that narrow reading would not extend to cover what the defendant is doing either. So there is no infringement.

Either way – invalid patent or no infringement – the defendant walks free. The patent holder cannot have it both ways. This type of squeeze argument holds that if a product or process used by an alleged infringer falls within the scope of a patent claim, but that product or process would have been known or obvious at the priority date, the claim must be invalid for lack of novelty or inventive step.

What the defendant must establish 🔗

Invoking the Gillette Defence is not simply a matter of pointing at old documents and claiming similarity. A defendant must methodically build the following three pillars of proof:

Identifying specific prior art: The defendant must locate concrete prior art – published documents, earlier patents, publicly used products or processes – that existed before the priority date of the plaintiff’s patent. Crucially, only prior art that was publicly known or used qualifies; secret or private prior use is generally not sufficient to anchor the defence.

Showing that the defendant’s conduct matches the prior art: The defendant must then demonstrate that what they are doing mirrors what the prior art disclosed – not something improved upon or materially different from it. Any deviation from the prior art that happens to fall within the patent claims could still constitute infringement, since those differences may themselves be covered. This comparison demands careful technical analysis, often supported by expert testimony.

Articulating the squeeze: Finally, the defendant must clearly frame the “squeeze” argument – showing the court that the patent claims, however they are construed, cannot simultaneously be valid and cover the defendant’s conduct. This requires close reading of claim language and scope alongside the prior art.

Gillette Defence under Indian patent law 🔗

India’s patent law system, grounded in the Patents Act, 1970, inherits much of its foundational architecture from British common law. The Gillette Defence, while not codified under that name, finds strong statutory support in two key provisions of the Act.

Section 64(1)(e) – revocation for lack of novelty 🔗

This provision allows a patent to be revoked if the invention, as claimed, was publicly known or publicly used in India before the priority date. India follows the principle of absolute novelty, requiring that an invention not be anticipated by previous publication in India or elsewhere under Sections 13(1)(a) and 13(2) of the Act. When a defendant shows that their product matches something already in the public domain, this ground for revocation becomes directly relevant.

Section 64(1)(f) – revocation for lack of inventive step 🔗

Under Section 2(1)(ja), “inventive step” is defined as a feature involving technical advance over existing knowledge or having economic significance, making the invention not obvious to a person skilled in the art. A lack of inventive step is an explicit ground for revocation under Section 64(1)(f). When a defendant’s conduct is essentially what a prior art document already disclosed, the argument that the patent claims covering that conduct lack inventive step flows naturally – which is the second limb of the Gillette squeeze.

Section 25 – opposition proceedings 🔗

Both pre-grant and post-grant oppositions under Section 25 of the Patents Act allow any interested person to challenge a patent on grounds of prior publication or lack of inventive step. These proceedings offer a formal channel through which a Gillette-style argument can be raised even before a full-blown infringement suit is initiated.

Indian case law 🔗

Indian courts have engaged with the underlying principles of the Gillette Defence on several occasions. In the Supreme Court’s decision in Bishwanath Prasad Radhey Shyam v Hindustan Metal Industries (1979), the court underscored that the grant of a patent does not guarantee its validity, and novelty can be challenged in infringement or revocation proceedings. More directly, in Strix Ltd v Maharaja Appliances Ltd (2010), the Delhi High Court recognised and applied the Gillette Defence when the defendant demonstrated that its product was based on prior art that predated the plaintiff’s patent.

How the Gillette Defence differs from other patent challenges 🔗

It is worth distinguishing the Gillette Defence from two related but separate defences: anticipation (lack of novelty) and obviousness.

An anticipation defence directly attacks the patent’s validity by showing the prior art discloses every element of the claimed invention. An obviousness defence challenges whether the invention involved a genuine inventive step. Both require the court to first construe the patent claims carefully, then measure them against prior art – a detailed, often expensive, technical exercise.

The Gillette Defence is different in that it aims to bypass the need for detailed claim construction altogether. The defendant essentially says: “Whatever your claims mean – narrow or broad – I am either not infringing or your patent is invalid.” It is a shortcut that collapses two separate inquiries (validity and infringement) into a single, factual comparison between the defendant’s conduct and the prior art. This makes it particularly attractive for summary proceedings, where avoiding the cost of full claim construction is valuable.

That said, some courts – including Canada’s Federal Court of Appeal – have noted that the Gillette Defence is not truly a freestanding, separate defence but rather a practical tool that operates as a cross-check on infringement and validity analysis. Even at the newly established Unified Patent Court (UPC) in Europe, which handled the defence for the first time in a dispute between SodaStream and Swedish company Aarke, the court accepted that prior art may be used in claim interpretation but found that the specific Gillette Defence argument in that case did not succeed on its facts.

Practical limitations of the Gillette Defence 🔗

Despite its elegance, the Gillette Defence has real-world constraints. First, the prior art must be publicly available – a prior secret use, even if the defendant can prove it, will generally not anchor this defence, because secret prior use does not render an invention unpatentable in most jurisdictions. Second, the defendant’s product or process must closely track the prior art. Any meaningful technical departure from the prior art – especially if that departure falls within the patent’s claims – can break the defence.

Third, the defence demands the defendant to be transparent about what they are doing technically. In practice, defendants may be reluctant to rely entirely on the Gillette Defence if they are not confident the factual comparison between their conduct and the prior art is airtight. It is important to ensure that the defence’s application suits the specific facts of the case – a weak factual foundation means the squeeze argument collapses entirely.

Why it matters for patent litigation strategy 🔗

The Gillette Defence fundamentally shifts the terrain of a patent dispute. Instead of fighting on the patent holder’s preferred ground – whether the defendant infringed carefully constructed claims – it redirects the court’s attention to a simpler, factual question: was what the defendant is doing already in the public domain? If the answer is yes, the patent simply cannot reach it, regardless of how broadly the claims are written.

For defendants in India, this defence is especially significant given the country’s robust prior art landscape in sectors like pharmaceuticals, traditional knowledge, and manufacturing processes. The Gillette Defence, as reflected in Sections 64(e) and (f) of the Patents Act, 1970, is regarded as a highly effective tool to establish the invalidity of a patent where the claimed invention lacks genuine novelty. Combined with India’s formal pre-grant and post-grant opposition mechanisms under Section 25, defendants have multiple strategic pressure points to deploy this argument.

For patent holders, the lesson is equally clear: overly broad claims are a vulnerability, not a strength. A claim written wide enough to capture competitors will, more often than not, also be wide enough to capture prior art – and that is precisely the trap the Gillette Defence is designed to spring.

What do you think? If a defendant’s product is functionally identical to a prior art design but differs in a minor technical detail – should that difference be enough to defeat the Gillette Defence, or should courts look at the overall similarity with what was already in the public domain? And given India’s rich repository of traditional knowledge as potential prior art, do you think the Gillette Defence could play a larger and more distinctive role in Indian patent disputes going forward?

References

1. https://www.legalserviceindia.com/Legal-Articles/gillette-defense-in-patent-infringement/
2. https://www.albright-ip.co.uk/2025/02/the-gillette-defence-at-the-upc-a-razor-sharp-strategy/
3. https://www.pinsentmasons.com/out-law/news/sodastream-case-upc-decides-gilette-defence
4. https://company360.in/blog/patent-infringement-in-india-and-defences-for-the-same/
5. https://www.indiacode.nic.in/handle/123456789/1392?locale=en
6. https://www.lexology.com/library/detail.aspx?g=7e87a96f-c83c-42d3-bc3f-cdd486a12068
7. https://stratjuris.com/decoding-inventive-step-for-patents-in-india/
8. http://www.sufficientdescription.com/2021/09/gillette-defence-and-prior-user-rights.html