In India finger prints are obtained instead of signatures particularly when the executant is illiterate. When a person puts thumb impression his name is written around the impression to confirm that the impression belongs to the person named. Similarly in cases where the signature of a person is illegible, his name in block letters is appended under the signature. Though these steps are precautionary, it is necessary that the full name of the executant is given so that the person affixing the thumb impression or signature is duly identified. Finger prints have certain characteristics such as arches, loops, whorls and composites. It is through the identification of these similarities the name of the person affixing the thumb impression can be ascertained.
If thumb impression is disputed, the party has no option but to send it for expert opinion. Unless the Court by a close observation comes to a decision that prima facie the thumb impression is genuine, it shall direct the parties to seek expert opinion. If the opinion of the expert thus obtained is not made the subject matter of examination and cross examination of the experts, mere opinion by itself shall not be considered as evidence.
[Ref.: Sec. 45 of the Indian Evidence Act, 1872; Emperor v. Babulal, 1928 (30) Bombay Law Reporter 321.]