The Delhi High Court has held that where there is a post-grant opposition based on an expert opinion to invalidate a patent under Section 25(2) of the Patents Act, the petitioner (who had acquired the patentee firm) can be allowed to cross-examine the expert under Section 79.
The Court in the case of Onyx Therapeutics v. Union of India observed that the case was of grant of a patent involving highly technical analysis by the expert witnesses, and that denial of cross-examination would violate the principles of natural justice.
The respondent had alleged that the right to cross examine in any proceedings before any IP Tribunal, including the Patent Office, is not an inherent or statutory right.
The court however held that technical analysis conducted by the expert witness, where the expert witness had provided his view, opinion or analysis of different prior art documents or literature and his opinion thereto, cannot constitute facts per se, and therefore in such cases, if cross-examination is prayed for, the same should be granted.
It also held that action of adjudicating authority reviewing its own decision suo moto, and denying cross-examination, is a manifest error of law.