High Court of Delhi at New Delhi | Decided: 10 September 2009 | I.A. No. 7441 of 2008 in C.S. (OS) No. 1206 of 2008 Bench: Hon’ble Dr. Justice S. Muralidhar Citation: 2009 SCC OnLine Del (C.S.(OS) No. 1206 of 2008)
Background
Strix Limited is a company incorporated in 1951 under the name Castletown Thermostats under the laws of the Isle of Man and was renamed Strix Limited in 1981. The company claims to be the world’s leading manufacturer of temperature controls and cordless interfaces for kettles, jugs and other water boiling appliances, with its controls being sold in over forty countries and used over one billion times a day by over twenty per cent of the global population. Its technology is embedded in products sold by well known brands including Philips, Tefal, Rowenta, Morphy Richards, Russell Hobbs, Braun, Kenwood and Bosch Siemens. The core function of Strix’s controls is to enable electric kettles to switch off automatically when the water boils and crucially, to protect the heating element from overheating even when the kettle is switched on without any water in it.
Strix holds a product patent bearing number 192511/95 in India for “Liquid Heating Vessels.” The patent was applied for on 9 June 1995 and was granted on 11 November 2005, remaining valid for twenty years from the date of application. The principal claim of the patent covers a liquid heating vessel comprising a liquid receiving container and an electrical heating element provided in thermal contact with the base of the container. The distinguishing feature of the invention is a thermally sensitive overheat control comprising at least two thermally responsive sensors arranged in good thermal contact with and at spaced apart locations on the base of the container or the element, which sensors operate individually in the event of the element overheating due to the vessel being switched on dry or boiling dry, so as to interrupt or reduce the supply of electrical energy to the element. The sensors in the Strix patent work by detecting the temperature of the heating element itself, not the liquid in the vessel. Strix claims to have first commercially deployed the technology in India in 2002 through its U10 Series Controls.
Maharaja Appliances Limited, the defendant, is an Indian company engaged in the manufacture and sale of electrical appliances including electric kettles. It is admitted that the defendant was purchasing electric kettles containing Strix controls from the plaintiff during 2005 and 2006. The defendant states that it found Strix’s products to be of inferior quality and consequently began importing electric kettles fitted with a different heating element from a supplier in China. The defendant maintained that it was merely a trader and had not undertaken any manufacturing activity in relation to the heating element itself. It further claimed that its Chinese supplier held a patent covering the heating element installed in the imported kettles, though it could not produce any details or documentation to that effect before the court.
Strix filed the present suit in 2008 alleging that the heating element in the Maharaja Whiteline electric kettle Model No. EK 172, which the defendant was marketing in India, infringed its patent No. 192511/95. Along with the suit, Strix filed I.A. No. 7441 of 2008 under Order XXXIX Rules 1 and 2 of the Civil Procedure Code, 1908, seeking an ad-interim injunction restraining the defendant from infringing its registered patent and specifically from manufacturing, using, selling or importing the Maharaja Whiteline kettle Model No. EK 172. The defendant resisted the injunction primarily by challenging the validity of Strix’s patent, contending that the invention lacked novelty and was rendered obvious by a prior European Patent and by raising the defence under Section 107A of the Patents Act, 1970 in relation to the alleged Chinese patent held by its supplier.
Issues for Determination
- Whether the plaintiff has made out a prima facie case of infringement of its patent No. 192511/95 in respect of the heating element technology used in the defendant’s Maharaja Whiteline electric kettle Model No. EK 172.
- Whether the defendant has raised a credible challenge to the validity of the plaintiff’s patent at the interlocutory stage, specifically whether the European Patent EP0469758 constitutes prior art that prima facie teaches or anticipates the plaintiff’s invention, such that the plaintiff’s patent lacks novelty or inventive step.
- What is the standard of proof or threshold that a defendant must meet at an interlocutory stage in order to raise a credible challenge to the validity of a patent so as to disentitle the patentee from interim injunctive relief.
- Whether the defence under Section 107A of the Patents Act, 1970 is available to the defendant on the ground that the Chinese supplier from whom the kettles were imported allegedly holds a valid patent for the product, in the absence of any documentary proof of such patent.
- Whether the plaintiff has sufficiently worked its patent in India so as to be entitled to seek injunctive relief and whether the balance of convenience and the test of irreparable harm favour the grant of an interim injunction.
Key Holdings of the Court
First, the court held that the plaintiff had made out a prima facie case of infringement of its patent No. 192511/95. The features of the defendant’s product, as set out in a comparative chart at paragraph 14 of the application, were found to be substantially similar to the features of the plaintiff’s patented invention. The defendant had not denied in its written statement that its product infringed the plaintiff’s patent and had confined its defence entirely to challenging the validity of that patent.
Second, the court held that the European Patent EP0469758 cited by the defendant does not constitute prior art that prima facie teaches or anticipates the plaintiff’s invention. The court found, upon examining the specifications and drawings of both patents, that the Strix patent and the European Patent operate on fundamentally different principles. The Strix patent sensors are linked to the heating element, detect the temperature of the element itself, are bimetallic actuators of the thermo-mechanical type, are mounted on a single carrier plate, can operate independently of each other and provide double pole protection. The European Patent sensors, by contrast, are located on the wall of the vessel and inside the vessel, detect the temperature of the liquid rather than the element, are thermistors which are purely electrical devices rather than thermo-mechanical ones, require additional circuitry and must work together. These differences are fundamental and not merely peripheral.
Third, the court laid down that in order to raise a credible challenge to the validity of a patent at the interlocutory stage, the defendant must place on record acceptable scientific material supported or explained by the evidence of an expert, demonstrating that the plaintiff’s patent is prima facie vulnerable to revocation. It is insufficient for a defendant to merely point to the existence of a prior patent and assert invalidity without more. The burden is heavier where, as in this case, there was no pre-grant or post-grant opposition to the plaintiff’s patent.
Fourth, the court rejected the defence under Section 107A of the Patents Act, 1970. The defendant had merely asserted that it had written to its Chinese supplier seeking information about the patent allegedly held by it and was awaiting a reply. The court held that the plaintiff could not be made to wait indefinitely for protection merely because the defendant had written to its supplier. In the absence of any documentation establishing the existence of a valid patent held by the Chinese supplier, the court would proceed on the basis that no such patent existed.
Fifth, the court rejected the argument that the plaintiff had not worked its patent in India. The defendant’s own case was that it had been purchasing the product from the plaintiff in 2005 and 2006, which established that the plaintiff had commercially exploited its patent in India. The court granted the ad-interim injunction restraining the defendant from manufacturing, marketing or otherwise infringing the plaintiff’s patent No. 192511/95 pending the final disposal of the suit.
Statutory Provisions Involved
Section 48 of the Patents Act, 1970 confers upon a patentee the exclusive right to prevent third parties from making, using, offering for sale, selling or importing the patented product in India without the patentee’s consent. This provision formed the foundation of Strix’s claim to injunctive relief, as it establishes the patentee’s right to enforce exclusivity against all third parties including importers of infringing products.
Section 3(d) and Section 3(f) of the Patents Act, 1970 enumerate categories of inventions that are not patentable. Section 3(d) excludes the mere discovery of a new form of a known substance which does not result in the enhancement of the known efficacy of that substance. Section 3(f) excludes the mere arrangement or rearrangement or duplication of known devices each functioning independently of one another in a known way. The defendant relied on Section 3(f) to argue that the plaintiff’s patent was merely a rearrangement of known elements and therefore not patentable. The court rejected this contention, holding that such an argument cannot be accepted on a bare averment without scientific literature and expert opinion to support it.
Section 107A of the Patents Act, 1970 provides that the importation of a patented product from a person who is duly authorised under the law to produce and sell or distribute the product shall not be considered an infringement of the patent. The defendant invoked this provision to argue that if its Chinese supplier held a valid patent for the heating element in question, the importation of kettles fitted with that element could not constitute infringement. The court held this defence to be unavailable in the circumstances since the defendant failed to produce any documentation establishing the existence or validity of any such Chinese patent.
Order XXXIX Rules 1 and 2 of the Civil Procedure Code, 1908 govern the grant of temporary and ad-interim injunctions. These provisions require the applicant to establish a prima facie case, demonstrate that the balance of convenience lies in its favour and show that refusal of the injunction would cause irreparable harm or injury. The court applied these well-established principles in assessing whether the interim injunction sought by Strix ought to be granted.
Reasoning of the Court
The court’s reasoning in this case proceeded along two principal tracks. The first concerned the substantive question of whether the plaintiff’s patent was prima facie valid and the second concerned the procedural and evidentiary standard that a defendant must meet at the interlocutory stage in order to defeat an injunction by raising a challenge to patent validity.
On the question of validity the court conducted a careful technical comparison between the Strix patent and the European Patent cited by the defendant as prior art. This comparison was based on the specifications, drawings and the comparative chart placed on record by the plaintiff. The court found that the two patents work on entirely different principles. The Strix patent protects the heating element itself from overheating by placing sensors directly in thermal contact with the element, so that the device switches off when the element reaches a critical temperature regardless of whether there is any liquid in the vessel. The European Patent, by contrast, protects against over-boiling of the liquid by sensing the temperature of the liquid through sensors placed on the wall and inside the vessel. If the vessel is empty, the European Patent sensors receive no signal and the element continues to heat unchecked, leading to potential damage. The court concluded that the technical problem addressed, the mechanism employed and the result achieved by the two patents are materially different and that the European Patent therefore cannot be said to teach or anticipate the Strix invention.
On the evidentiary standard for raising a credible challenge to patent validity at the interlocutory stage, the court took a firm and clear position. It held that a defendant cannot discharge this burden merely by pointing to the existence of a prior patent and making a bare assertion that the plaintiff’s invention lacks novelty or involves no inventive step. The defendant is required to place on record acceptable scientific material, supported by or explained through expert evidence, that demonstrates a prima facie vulnerability in the patent. The court drew support from the Australian decisions in Beecham Group Ltd. v. Bristol Laboratories Pty Ltd. and Hexal Australia Pty Ltd. v. Roche Therapeutics Inc. for the proposition that the party asserting invalidity bears the onus of showing that want of validity is a serious or triable question. The court further noted that this burden is reinforced in cases where, as here, there was no pre-grant or post-grant opposition to the patent. The absence of any challenge during the patent prosecution process makes it more difficult for a defendant to raise a credible challenge for the first time in infringement proceedings without scientific and expert backing.
The court also dealt firmly with the defendant’s attempts to rely on Section 107A and the alleged Chinese patent as a defence to infringement. The court reasoned that the defendant, being an established business with a substantial turnover, was not in the position of an innocent importer who had no knowledge of the plaintiff’s patent. The defendant had previously purchased the very same product from the plaintiff itself and was therefore fully aware of the existence and scope of the plaintiff’s patent. In these circumstances, having switched suppliers to China and continued to market the same product in India, the defendant carried an obligation to ensure that its imports did not infringe the plaintiff’s patent. Placing the burden on the plaintiff to await the defendant’s correspondence with an unnamed Chinese supplier before seeking enforcement of its patent rights was, in the court’s view, untenable.
On the question of working the patent in India, the court found that the defendant’s own admission that it had been purchasing the product from the plaintiff in 2005 and 2006 settled the matter conclusively. Commercial exploitation of a patent by marketing the patented product in India through sales to a local buyer constitutes working the patent within the meaning of the Patents Act, 1970 and no further documentary proof of manufacture within Indian territory was required. The court accordingly held that all three requirements for the grant of an interim injunction, being prima facie case, balance of convenience and irreparable harm, were satisfied in favour of the plaintiff.
Doctrinal Significance
This judgment makes a valuable and precise contribution to the developing body of Indian jurisprudence on the standard of proof required of a defendant who seeks to defeat an interim injunction in patent infringement proceedings by challenging the validity of the plaintiff’s patent. The court’s ruling that a credible challenge to patent validity at the interlocutory stage requires scientific material supported by expert opinion and that a mere reference to a prior patent without technical analysis of its relationship to the suit patent is insufficient, sets an important threshold that protects validly granted patents from being undermined by bare and unsubstantiated invalidity claims. This standard is consistent with the approach adopted in Australian patent jurisprudence and fills a gap in Indian patent law, where the precise evidentiary requirement for raising an invalidity defence at an interlocutory stage had not been clearly articulated before this decision.
The judgment also reinforces the significance of the absence of pre-grant and post-grant opposition proceedings as a factor that raises the evidentiary burden on a defendant challenging validity in infringement proceedings. Where a patent has proceeded through grant without any opposition, the presumption of validity that attaches to a granted patent under the Patents Act, 1970 carries greater weight and a defendant who did not exercise available statutory rights to oppose the grant cannot easily be heard to mount a credible invalidity challenge for the first time in infringement proceedings without substantial technical evidence. This principle, though grounded in common sense, is clearly articulated in this judgment and has relevance for patent litigation practice in India.
The treatment of Section 107A of the Patents Act, 1970 is also significant. The court declined to permit the defendant to invoke this provision as a shield against enforcement of the plaintiff’s patent merely on the basis of an unverified assertion that its Chinese supplier held a relevant patent. The court’s reasoning that a defendant with actual knowledge of the plaintiff’s patent, arising from a prior commercial relationship with the patentee, carries a positive obligation to verify the intellectual property credentials of any alternative supplier before importing and marketing competing products, introduces a doctrine of due diligence that is commercially sensible and consistent with the purposes of patent protection. It ensures that the parallel importation defence under Section 107A cannot be deployed as a tactical device to delay injunctive relief without any factual foundation.
The judgment is additionally notable for the methodology it adopts in conducting technical patent comparison at the interlocutory stage. Rather than treating the comparison of prior art with the suit patent as a matter exclusively for trial, the court engaged in a detailed examination of the specifications and drawings of both patents to assess prima facie whether the prior art taught the plaintiff’s invention. This approach demonstrates that Indian courts are willing and able to engage with technical complexity in patent disputes at the interlocutory stage and that the grant or refusal of interim injunctions in patent cases should be grounded in an informed technical assessment rather than a mechanical application of the three-pronged test without reference to the substance of the patent claims.
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