The main issue raised in the instant cause is whether the trial court abused its discretion when it excluded the testimony of the three defense witnesses concerning the whereabouts of the defendant and his girl friend from roughly 9:00 p. m. to 1:00 a. m. on October 16,1974.2
*53Crim. E. 12.1 provides:
“Whenever a defendant in a criminal case proposes to offer testimony to establish an alibi on his behalf, he shall, not less than seven days before trial, file and serve upon the prosecuting attorney a notice in writing of his intention to claim alibi. The notice shall include specific information as to the place at which the defendant claims to have been at the time of the alleged offense. If the defendant fails to file such written notice, the court may exclude evidence offered by the defendant for the purpose of proving such alibi, unless the court determines that in the interest of justice such evidence should be admitted.” (Emphasis added.)
The purpose of pre-trial discovery rules such as the alibi notice requirement of Crim. E. 12.1 is to insure a fair trial for both the state and the defendant. Williams v. Florida (1970), 399 U. S. 78; Commonwealth v. Shider (1966), 209 Pa. Super. 133, 224 A. 2d 802. In keeping with that purpose, Crim. R. 12.1 requires the defendant to file timely notice of his intent to raise an alibi defense (State v. Focht [1974], 37 Ohio St. 2d 173, 174); but it also grants the trial court the discretion to waive that requirement and to admit unfiled alibi testimony if it is in the “interest of justice” to do so.
If the alibi testimony does not surprise or otherwise prejudice the prosecution’s case (see State v. Thayer [1931], 124 Ohio St. 1, 4, and see, also, State v. Nooks [1930], 123 Ohio St. 190, 193-194), and if the defense operated in good faith when it failed to give proper notice of an alibi defense (see State v. Adair [1970], 106 Ariz. 4, 469 P. 2d 823, 826), then the “interest of justice” may require admission of the unfiled alibi testimony.3 After an examina*54tion of the instant canse for good faith on the part of the defense, surprise to the prosecution, and prejudice to either party, we find that the trial court’s exclusion of testimony concerning the-whereabouts of defendant and Miss Ayers on the evening* of October 16 did not serve the “interest of justice.”
Nothing in the record of the instant cause reveals bad faith on the part of the defense. Defense counsel filed notice-' concerning Smith’s whereabouts on October 18, and explained their failure to do so for the 16th by stating that they believed the defendant’s assertion that he was elsewhere on the 16th to be implicit in his denial of the charge of selling marijuana, in person, to agents Krouskop and Schroeder. Although counsel were mistaken in that belief (see State v. Nooks [1930], 123 Ohio St. 190, 193-194), they were not engaged in the poker game strategy which alibi notice requirements are designed to prevent. Williams v. *55Florida, supra, at page 82. It was, therefore, not necessary for the trial court to impose the sanctions of Crim. R. 12.1 on the defense.
The excluded testimony of the three defense witnesses concerning the whereabouts of the defendant and his girl friend on the evening of October 16 did not constitute surprise testimony by last-minute or out-of-town witnesses whose credibility the prosecution had no opportunity to probe. State v. Thayer, supra, at page 4. The prosecution knew from the time of defendant’s arrest that the testimony of the defendant, his brother and his girl friend as to the whereabouts of defendant and Ayers on the evening of October 16 would be crucial because its case was based on police agents’ statements placing all three at the scene of the crime.4 Moreover,, there is no indication that the prosecution would have presented its case differently had it known of the specific alibi testimony in advance. Indeed, the prosecution had clearly combed the evidence for material to impeach the testimony of the three defense witnesses com cerning their whereabouts on the evening in question. (Even before the defense called Margo Ayers to the witness stand, the prosecution elicited testimony from agent Schroeder designed to lead jurors to infer that Ayers recognized ¡Schroeder from the evening of the sale.) Furthermore, any incidental element of surprise which the excluded testimony .¿might have contained could have been remedied without prejudice to either party had the trial court granted defense counsel’s request for- a brief continuance to allow ,the prosecution additional discovery time..
Admission of the unfiled alibi testimony would, not have surprised or otherwise prejudiced. the prosecution. .Further, the exclusion of that testimony was sufficiently *56damaging to the defendant to endanger his chances of obtaining a fair trial. Because a number of defense witnesses challenged the reliability of both the prosecution’s tapes .and of agent Krouskop,5 the defendant stood to benefit greatly if the jury believed his account of his activities on the evening of the alleged sale. Once the trial court precluded the three defense witnesses from testifying concerning the whereabouts of defendant and Ayers that evening, defendant and his girl friend were reduced to testifying that they were not at the sale without being allowed to explain where they were. That silence certainly diminished their credibility. Commonwealth v. Shider, supra6 Since the alibi evidence was not withheld from the prosecution in bad faith, since it would not have surprised or otherwise prejudiced the prosecution, and since its • admission was necessary under the facts of the instant cause to insure defendant a fair trial, we find that the trial court’s exclu*57sion. of that alibi testimony defeated the policy of justice and fair play underlying Crim. B. 12.1 and, therefore, constituted an abuse of discretion.
For the forgeoing reasons, the judgment of the Court of Appeals is reversed, and the cause is remanded to the Court of Common Pleas for a new trial.
Judgment reversed.
O’Neill, C. J., W. Brown, Steen and Sweeney, JJ., concur. HeRbeet, Celebrezze and Locher, JJ., dissent. Stern, J., retired, assigned to active duty under authority of Section 6(C), Article IV, Constitution, sitting for P. Brown, J.In their briefs and arguments before this court, the parties discussed the constitutionality of Crim. R. 12.1 as it applies to the alibi testimony of a defendant. Since we have found exclusion of that testimony to be an abuse of discretion in the instant cause, we decline to decide the issue.
The syllabus of the Nooks opinion provides as follows:
“Upon the trial of persons jointly indicted for grand larceny, a verdict of guilty will not be disturbed where no abuse of discretion appears in the trial court excluding testimony offered by the accused for the purpose of proving an alibi, no notice of which has been given the state as provided in Section 13444-20, General Code, such proffered testimony being ‘for the purpose of showing the whereabouts of said *54defendant * * * and to disprove the testimony of * * * witness for the prosecution,' it not appearing that such proffer went to any other subject than that of alibi.” (Emphasis added.)
The Nooks and Thayer opinions were both responses to appellate court rulings that certain alibi testimony did not fall within the alibi notice requirement. In holding that the defense should have filed notice of alibi testimony even though that testimony impeached the credibility of a state witness (Nooks, supra, at page 193) or contradicted state testimony in support of the charge (Thayer, supra, at page 4) both opinions are consistent with the court’s ruling that the trial court abused its discretion in the instant cause by excluding the alibi testimony of Smith and Ayers. We do not hold that the testimony of Smith and Ayers was not alibi testimony because it tends to contradict the testimony of state witness Krouskop, but merely maintain, in the language of the Nooks opinion, at page 194, that “it affirmatively appears from this record that the trial court abused its discretion * * (Emphasis added.)
That the court in the Adair opinion considered good faith on the part of the defendant to be important is revealed in the reasons it gives, at page 7, for excluding alibi testimony on the facts before it:
“* * * Nowhere in the record is there given any reason for the failure to include the witness in the notice nor does the defendant, in his brief on this appeal, point to any explanation for such omission.”
Implicit support for the proposition that the state will' not br prejudiced by the unfiled alibi defense of a witness whose identity and general connection with the alleged crime, is known to the prosecution is found in Federal Rule of Criminal Procedure 12.1(e) which allows the defendant to testify concerning his.alibi even if he has failed to comply with the alibi notice rule.
Botli agents had access to the tapes after they were delivered to the District Enforcement Agency office. Portions of the taped conversation introduced by the prosecution as evidence of the sale were identified by several defense witnesses as actually occurring on October 17 when the three defense witnesses and some of their friends ran into Krouskop at a Lima bar. In. addition, the testimony elicited from the filling station owner implied that a conversation taped at his. gas station between two parties whose cars were parked as Krouskop tésti-fied should have included three or four rings of a bell as the cars rolled over the rubber hose designed to alert the attendant to a waiting customer.
Defendant’s time card, which was punched out by him, showed that he did not leave his place of employment in the afternoon of the 16th until after the time Krouskop testified to meeting with him to arrange the sale of marijuana. In addition, 19 witnesses, including a farmer who had no connection with the defendant or members of his peer group, testified to witnessing Krouskop’s use, sale or pandering of drugs (mostly marijuana) during a four-year period of time before defendant’s trial.
The situation in the instant cause is similar to that in Commonwealth v. Shider, supra (209 Pa. Super. 133), where the court, found' that refusing to permit Mrs.- Shider to-testify after a neighbor testified to seeing the Shiders at home at the time of the crime was highly prejudicial to the defense. . ■