Concurring Opinion by
Mr. Justice Pomeroy:I join in the opinion of the Court, since I am satisfied that in the four cases here under review, Pa. R. Crim. Proc. 310 was disregarded.1 I add this *111brief supplement merely to emphasize Mr. Justice Eagen’S statement in his opinion for the Court, that “[tjhere is no question good arguments can be made for the proposition that the pre-trial discovery rules should be liberalized.” Indeed, the respondents’ brief advances such arguments. While the trend of recent writing2 appears to have been in favor of increasing the range of permissible discovery, it must be acknowledged that “the extent to which pre-trial discovery should be permitted in criminal cases is a complex and controversial issue.” Note of Advisory Committee on 1966 Amendments to Rule 16 of the Federal Rules of Criminal Procedure, 39 F.R.D. 175 (1966). Without here engaging in extended discussion of the subject, I, for one, see merit in a rule which would permit inspection by a defendant of records or reports of physical or mental examinations in the possession of the government made in connection with a particular case, and which are relevant. This is in line with the amended Federal Rule 16(a), which indeed would bear study in its entirety in connection with any revision of our own rule.
As a matter of first impression, I would have difficulty agreeing that the deviation from our rule presented a case of “extreme necessity”, as that phrase is used in Carpentertown Coal *111and Coke Co. v. Laird, 360 Pa. 94, 61 A.2d 426 (1948). We should, moreover, be zealous not to permit tlie remedy of prohibition to be utilized to review what may be, in essence, an exercise of discretion by the trial court. The propriety of our entertainment of a petition for a writ of prohibition in connection with a pre-trial discovery order in a criminal case has, however, been expressly decided in the affirmative. Commonwealth v. Caplan, 411 Pa. 563, 192 A.2d 894 (1963). Without foreclosing possible later re-examination of that holding, I accept it for the present.
See, inter alia, bibliographical material listed in Note of Advisory Committee on 1966 Amendments to Bule 16 of the Federal Buies of Criminal Procedure, 39 F.R.D. 175 (1966); see also the selected bibliography on criminal discovery in 2 A. Amsterdam, Trial Manual for the Defense of Criminal Cases, 3-56; L. Hall, et al. Modern Criminal Procedure, 1022 et seq.