Exploring expert evidence in patent matters

By Pravin Anand and Prachi Agarwal, Anand and Anand

‘Expert opinion’ has been defined under section 45 of the Indian Evidence Act 1872 as “when the court has to form an opinion upon a point of foreign law or of science or art, or as to identity of handwriting or finger impressions, the opinions upon that point of persons specially skilled in such foreign law, science or art or in questions as to identity of handwriting or finger impressions are relevant facts. Such persons are called experts.”

Pravin Anand
Managing partner
Anand and Anand


Patent matters are highly technical in nature, relating to new inventions in various scientific and technical fields, so the opinions of experts in these fields, whose testimony is trustworthy, reliable and supported by documents, becomes crucial.

In two recent Indian patent cases where the final arguments were heard after a fully-fledged trial, the courts emphasized the importance of expert testimony in patent matters to adjudicate upon the issue of patentability of the invention and to prove infringement.

Expert evidence is required in matters that are outside the knowledge and experience of the layperson, and the scientific question involved is assumed to be not within the court’s knowledge.

As has also been pointed out by the Apex Court in India, “where the science involved is highly specialized and perhaps even esoteric, the central role of an expert cannot be disputed”.


In a recent Delhi High Court decision dated 2 February 2017, in F Hoffmann La Roche and Another v Natco Pharma, and F Hoffmann La Roche and Another v Dr Reddy’s Laboratories and Another, certain guidelines have been provided regarding procedures in patent matters that involve technical expert witnesses and the necessity of rules to be drafted to refine and formulate the procedures for expert testimony.

Prachi Agarwal
Managing associate
Anand and Anand

One of the issues that had arisen was that the usual practice in patent matters is that expert testimony is filed at the stage of evidence, after all pleadings in the matter have been filed by the parties, and therefore the pleadings may not necessarily cover the specific technical principles and grounds taken up by the experts in their evidence at the later stage. In view of this, the following guidelines were provided:

  • The pleadings have to be more specific. A party pleading that the patent is liable to be revoked on one of the grounds would be required to plead particulars of that ground. Similarly, the patentee would be required to plead why the invention is inventive;
  • An expert cannot give his evidence beyond the scope of pleadings as per the Indian Code of Civil Procedure, 1908;
  • When the documents are being filed at the initial stage of the suit, there should be a report by the technical expert that gives the essential points to be made by the expert;
  • In cases where an expert report is not filed, as long as the deposition of the expert, which is filed at the later stage, is within the confines of the pleadings, no difficulty will arise;
  • An expert remains a witness of the party litigant examining him or her, and whom the opposite party litigant has a right to cross-examine;
  • Since no rules are found to have been drafted, the judge has recommended to the Chief Justice to refer this case to the Rules Committee for amendment of the rules under the Code of Civil Procedure, 1908;
  • The issues in a case should be detailed and clearly defined, and should crystallize the real issue in controversy;
  • The onus of invalidity is on the defendant, and the defendant should therefore lead evidence on that issue in the first instance. Under current practice, plaintiffs lead evidence first on all the issues, even including those where the onus is on the defendants.


The above-mentioned guidelines will prove beneficial in refining the patent litigation framework and aid in adjudicating the matter in an efficient and timely manner.

Ways in which the patent litigation framework may be made more structured by litigators include:

  • Identify an expert at the time of drafting the pleadings so that a short report authored by such an expert can be incorporated in the pleadings;
  • The expert report should be precise and include all relevant prior art and scientific principles;
  • The pleadings and issues should be precise and in consonance with the expert report;
  • Issues and the onus of proving the issues should be as per the grounds taken in the pleadings and the documents and expert reports of both the parties.

Pravin Anand is the managing partner of Anand and Anand, and Prachi Agarwal is a managing associate at the firm

Anand and Anand

Anand and Anand

B-41, Nizamuddin East,

New Delhi 110013, India


Contact details:

Tel: +91 120 405 9300

Email: Pravin@anandandanand.com

Email: Prachi@anandandanand.com