When the Court has to form an opinion upon a point of foreign law or of science or art, or any other field, or as to the identity of handwriting or finger impressions, the opinions upon that point of persons specially skilled in such foreign law, science or art, or any other field, or in questions as to the identity of handwriting or finger impressions are relevant facts and such persons are called experts.
https://www.leadindia.law/bsa-section-39-opinions-of-experts