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India – High Court Compares Essential Features

Under the Indian Patent Act a patent is available on an invention that is new, useful and is not obvious to the person skilled in the art. The invention, a product or a process, must satisfy the test of constituting an inventive step, which means the improvement must produce a new result or a new or better article. In the case Strix Limited vs Maharaja Appliances Limited, which recently came up before the Delhi High Court, the technology in use was claimed to be a part of the public domain.

Strix holds a product patent number IN 19211 entitled Liquid Heating Vessels, which was granted on November 11 2005 and is valid for twenty years from the date of filling (June 9 1995). The claim of Strix’s patent is that of a liquid receiving container and an electrical heating element provided in thermal contract with the base of container.

Maharaja Appliances challenged the validity of Strix’s patent using a prior art EP 469758 called A Temperature Control Device for a Fluid Heating Vessel granted on April 3 1998.

The court compared the two patents in their essential features and the way the technology worked and decided to grant an interim injunction.

Strix sought an ad-interim injunction to restrain the defendant from manufacturing and selling electric kettles using their patented technology. Strix claimed to be a leading manufacturer of temperature controls and cordless interfaces for kettles, jugs and a wide range of water boiling appliances. Their inventions are designed to work in conjunction with the heating element of kettles and are means to automatically switch off kettles when the water boils, thus protecting the kettles from getting damaged in case they are not filled with liquid. The defendants averred that they imported the product from a manufacturer in China, who holds a valid patent for the heating technology.

Maharaja Appliances’ challenged the validity of Strix’s patent on the ground of being a mere workshop improvement on the existing product. The court called for the specifications of the two patents and examined them to arrive at the crux of the technology. While reading the specification, the court found that the prior art cited by the defendant relates to a control device that serves to sense ambient temperature and controls or adjusts the set point at which power is reduced to the heating element to prevent the fluid boiling over. This implies that it is a temperature control device for a liquid heating vessel comprising liquid temperature sensing means adopted to provide a liquid temperature indication in the vessel and control means adopted to regulate heat supply to the liquid during heating.

However, Strix’s patent was found to work on a different principle. The comparison of essential features revealed that Strix’s technology is centred on heating and cutting off supply to the element, with or without liquid in it. It is not directed at sensing the temperature of the liquid, but the temperature of the element.

The court concluded that the essential difference between the two products is that the patent for Strix’s product prevents the overheating of the element, while that of the defendant prevents boiling over of the liquid. Thus, there is a fundamental difference in the way the two technologies work, ruling out a teaching by prior art. Moreover, Strix’s patent provides a double protection to the device from getting damaged, while the prior art does not.

The Court also found that the defendant was unable to show that the Chinese supplier, from whom it is purchasing the infringing product, holds a patent for it. Maharaja Appliances knew that Strix holds a valid patent for the product that it was marketing and was also purchasing the product from Strix from 2005 to 2006. Therefore, there was an obligation on Maharaja Appliances, even while it imported the product from China, to ensure that it was not violating Strix’s patent. Strix was thus held entitled to enforcement and protection of its patent from other manufacturers, sellers and importers. Accordingly, the court allowed an interim injunction restraining the defendant, its agents, servants and all others working for it from manufacturing and/or marketing the electric kettle or otherwise infringing in any manner on the Strix’s patent.