Judgment :- 1. The petitioner is the defendant in a suit filed by the plaintiff-respondent on a promissory note. The note is alleged to have been executed by the petitioner in favour of one Kariyan. Out of the amount due under the promissory note, the petitioner is alleged to have repaid Rs. 300/- and made an endorsement on the pro-note. Kariyan subsequently assigned his rights under the promissory note to the respondent, who is the plaintiff in the suit. The petitioner resisted the suit and denied the execution of the promissory note, the receipt of consideration and also the signature or thumb impression of the alleged endorsement. The respondent tiled I. A. No. 1829 of 1977 to send the promissory note to the Finger Print Expert, Trivandrum. The application was allowed and the promissory note was sent for expert opinion. The opinion of the expert is that the thumb impression on the promissory note is that of the revision petitioner. The revision petitioner challenged the correctness of the above opinion and filed I.A. No. 434 of 1978 praying that the suit promissory note be sent to another expert for comparison and report. The Court passed the impugned order dismissing the petition on the ground that there is already the opinion of an expert and it is not necessary to obtain another report. 2. The reasoning of the Munsiff is challenged. According to the petitioner, it is within his rights to get the report of another expert and satisfy the Court that the opinion already before it is wrong and unreliable. The Court, according to the petitioner, should have allowed his prayer for sending the document to another expert. 3. S.45 of the Indian Evidence Act deals with opinion of experts. Under the said provision, 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 matters are relevant facts. The section does not say that an opinion expressed by an expert is conclusive on the matter covered by it. On the other hand, it is a well-recognised fact that an expert's evidence being only an opinion, it is upto the parties to let in evidence challenging its correctness and it is upto the Court to form its own conclusions on the evidence. On the other hand, it is a well-recognised fact that an expert's evidence being only an opinion, it is upto the parties to let in evidence challenging its correctness and it is upto the Court to form its own conclusions on the evidence. When direct evidence is forthcoming on the matter spoken to by an expert, the Court is not precluded from acting on such direct evidence in preference to the report of an expert. The value of the evidence of an expert would vary according to circumstances and also will depend upon the reasons given by him in support of his opinion. The value of an expert's opinion should be adjudged in the same way as the evidence of any other witness. The reasons given by him in forming the opinion are always open to scrutiny and the soundness of the view has to be tested in the light of the reasons given. It is always open to the opposite party to place materials before the Court to shake the foundation on which an expert opinion is formed. Such materials may be in the form of cross-examination of the expert himself or other counter-evidence. The counter-evidence may be the opinion of another person who is equally an expert in the matter which forms the issue in the case. Therefore, the reasons given by the Court for rejecting the petitioner's request to send the document for the opinion of another expert is not sustainable. 4. I may refer here to the decision of this Court in Narayana Kekannaya v. Dertnjathaya (1961 KLT. 960). In that case, a document was sent to a Calligraphic expert at Delhi for his opinion at the instance of the plaintiff After his report was received in Court, the defendant applied that the same document be sent to another expert at Madras for his opinion. The prayer was objected to by the plaintiff on the ground that once an expert opinion is available in the case, another should not be called upon unless and until the Court found the first opinion unacceptable. The objection was overruled by the trial court. The decision was challenged in revision. The prayer was objected to by the plaintiff on the ground that once an expert opinion is available in the case, another should not be called upon unless and until the Court found the first opinion unacceptable. The objection was overruled by the trial court. The decision was challenged in revision. Madhavan Nair, J. confirmed the order of the trial court and held that there is no rule of law, or of practice, that when a witness has been called in by one side to testify to a particular fact, the court should adjudicate the merit of his testimony before another witness for the opposite side can be allowed to speak on the same fact. The identical principle applies in the instant case. There are no sufficient reasons for disallowing the request of the petitioner that the document should be sent to another expert. 5. An objection is raised that the revision petition itself is not maintainable in view of the proviso to S.115 of the Code of Civil Procedure. The proviso, no doubt, says that the High Court shall not vary or reverse any order made or any order deciding an issue, in the course of a suit or other proceeding. But this proviso itself contains two exceptions. The exceptions are cases where (a) the order, if it had been made in favour of the party applying for the revision would have finally disposed of the suit or other proceeding, and (b) the order, if allowed to stand, would occasion a failure of justice or cause irreparable injury to the party against whom it was made. The second exception is applicable in this case. If the order passed by the Munsiff is to stand, the petitioner would be precluded from establishing the unsoundness of the opinion of the expert which is already before court. 6. It is argued that the petitioners' remedy lies in cross-examining the expert in order to show that his opinion cannot be acted upon. Assuming that the privilege is available to him, it is equally his right to examine witnesses of his choice and let in evidence which according to him, would support bis case. This right is denied to him by the order passed. Assuming that the privilege is available to him, it is equally his right to examine witnesses of his choice and let in evidence which according to him, would support bis case. This right is denied to him by the order passed. Equally untenable is the plea that the motion to send the document for the opinion of another expert should be made after the close of the evidence on the side of the plaintiff. Any direction to postpone sending of the document to another expert would amount to depriving the petitioner of materials that would be otherwise available to him to cross-examine the expert whose opinion is now before court. The revision petition is accordingly allowed. The order passed by the court below is set aside and the document will be sent to another expert as desired by the petitioner-defendant on his meeting the expenses thereof. The parties will bear their respective costs. Allowed.