In the case of patent infringement, courts must carefully examine the asserted patent's claims and the allegedly infringing product to determine whether the latter incorporates the essence of the invention claimed. One such approach used to evaluate patent infringement is the "pith and marrow" test, which was recently applied in the case of Sotefin SA v. Indraprastha Cancer Society and Research Centre (2022:DHC:595). This article delves into the significance of the pith and marrow test through a case study involving a patent infringement lawsuit in India.

The Suit Patent: Liquid Heating Vessels:
In the case at hand, the Plaintiff obtained a patent for "Liquid Heating Vessels" (Patent No. 192511/95) on 11th November 2005, claiming priority from a UK application dated June 9, 1994.

The patent was valid for twenty years from the date of application, expiring on 8th June 2015. The Plaintiff alleged that they had been using the invention described in the Suit Patent since 2002.

The key claim of the Suit Patent revolves around a liquid heating vessel comprising a liquid receiving container and an electrical heating element in thermal contact with the base of the container.

The Infringement Lawsuit:
The Plaintiff initiated legal proceedings against the Defendant, asserting that the Defendant's product, the "Maharaja Whiteline Model No. EK 172," infringed upon the Suit Patent. To establish infringement, the court had to evaluate whether all the essential features claimed in the Suit Patent were present in the Defendant's product.

The Pith and Marrow Test:
In patent infringement cases, courts traditionally perform a claim-by-claim analysis, comparing each element of the patent claims with the corresponding features of the accused product. However, the recent case of (2022:DHC:595) Sotefin SA v. Indraprastha Cancer Society and Research Centre introduced a different approach�the "pith and marrow" test.

"The pith and marrow test emphasizes that to establish patent infringement, it is not necessary to engage in meticulous and detailed specifications comparisons. Instead, the court should focus on the core or essence of the invention claimed in the patent. In other words, the court should identify the heart of the invention and determine whether the accused product infringes upon that core."

Application of the Test:
In the present case, the court applied the pith and marrow test to assess the Defendant's product, Maharaja Whiteline Model No. EK 172, against the Suit Patent. The court observed that the Defendant's product utilized temperature controls that, in essence, infringed upon the core of the invention claimed in the Suit Patent. By incorporating similar heating mechanisms and thermal controls in their product, the Defendant's product was found to be in violation of the pith and marrow of the patented technology.

The concluding Note:
The application of the pith and marrow test in the case of (2022:DHC:595) Sotefin SA v. Indraprastha Cancer Society and Research Centre represents a notable shift in the evaluation of patent infringement in India. This approach simplifies the process by directing the court's attention to the essence of the patented invention. It enables a more focused and efficient analysis, reducing the need for exhaustive comparisons of detailed specifications.

In the case discussed, the court effectively used the pith and marrow test to conclude that the Defendant's product infringed upon the Suit Patent's core innovation. This case demonstrates that the pith and marrow test can serve as a valuable tool in patent litigation, promoting clarity and expeditious resolution of infringement claims.

The Case Law Discussed:
Case Title: Strix Ltd vs Maharaja Appliances Limited
Date of Judgement/Order:20/10/2023
Case No. CS(COMM) 806/2017
Neutral Citation No: 2023:DHC:7667
Name of Hon'ble Court: High Court of Delhi
Name of Hon'ble Judge:Pratiba M Singh, H.J.

Disclaimer:
Information and discussion contained herein is being shared in the public Interest. The same should not be treated as substitute for expert advice as it is subject to my subjectivity and may contain human errors in perception, interpretation and presentation of the fact and issue involved herein.

Written By: Advocate Ajay Amitabh Suman, IP Adjutor - Patent and Trademark Attorney
Email: [email protected], Ph no: 9990389539