Dissenting Opinion by
Mr. Justice Pomeroy:In Commonwealth v. Futch, 447 Pa. 389, 290 A. 2d 417 (1972), this Court adopted “the federal approach” to evidence obtained during an unnecessary delay prior to arraignment, and announced a procedural rule excluding all evidence so obtained from admission at trial.1 Earlier this year, in Commonwealth v. Riggins, 451 Pa. 519, 304 A. 2d 473 (1973), we carefully considered the applicability of the Futch decision to a confession obtained during a period of unnecessary delay following an arrest in 1969 and, refusing implicitly to hold such a confession without more inadmissible, we instead applied the “totality of the circumstances” approach of our pre-Futch law.2 Today, however, the Court ignores Biggins and removes all restrictions on the retroactive application of Futch, at least as far back *552as January 1, 1965, the effective date of former Rule 116 of The Pennsylvania Rules of Criminal Procedure (predecessor of the present Rule 118).3 In my opinion this may well prove to be costly in terms of the administration of justice and futile in terms of correction of police procedures. I must dissent.
Like its federal prototypes, McNabb v. United States, 318 U.S. 332, 87 L. Ed. 819 (1943) and Mallory v. United States, 354 U.S. 449, 1 L. Ed. 2d 1479 (1957), our decision in Fuich was not based on constitutional considerations. The exclusionary rule we promulgated was grounded on the Court’s supervisory powers over the administration of justice in the courts of this Commonwealth. We have heretofore consistently denied retrospective effect to our supervisory rulings, even as to matters as closely related to the fairness of trial proceedings as jury instructions, see Commonwealth v. Spencer, 442 Pa. 328, 275 A. 2d 299 (1971); Commonwealth v. O’Neal, 441 Pa. 17, 271 A. 2d 497 (1970); Commonwealth v. Scoleri, 399 Pa. 110, 160 A. 2d 215 (1960).
The effective date of a new rule of evidence designed to control police conduct should be determined, in my view, by the same considerations which would govern a novel ruling of constitutional law. See Fuller v. Alaska, 393 U.S. 80, 21 L. Ed. 2d 212 (1968). As these have been formulated by the United States Supreme Court, they include: (1) the purpose to be served by the new standards, (2) the extent of the reliance by law enforcement authorities on the old standards, and (3) the effect on the administration of justice of a retroactive application of the new standards. Where on balance these considerations do not *553favor retroactivity, the current federal practice is to apply the new standard only where prohibited conduct takes place after the announcement of the rule. Desist v. United States, 394 U.S. 244, 22 L. Ed. 2d 248 (1969); Williams v. United States, 401 U.S. 646, 28 L. Ed. 2d 388 (1971). Examining Futch in this light, I can only conclude that its purpose will be fully realized by a solely prospective application.
The Futch exclusionary rule contributes nothing to the certainty of the judicial fact-finding process. As Mr. Justice Eagen pointed out in his concurring opinion in Commonwealth v. Tingle, 451 Pa. 241, 301 A. 2d 701 (1973), the rule is directed entirely to police conduct prior to trial and operates irrespective of the reliability or probative value of the evidence excluded. One may hope that the threat of exclusion will help to deter dilatory or illegal police conduct, but it can hardly be supposed that application of the exclusionary rule to events long past will add anything to the rule’s deterrent force for the future. On the other hand, the Court’s opinion may have grave repercussions on the administration of justice. No one knows how many prosecutions have been instituted since January 1, 1965 in reliance on our pre-Futch rules of admissibility, but there must have been a great many. Now, it appears, any defendant convicted on the basis of evidence which under Futch should be excluded is entitled to a new trial, regardless of the fairness of his original trial. I see nothing to be gained from saddling our judicial system with this potentially staggering burden.4
*554Mr. Chief Justice Jones and Mr. Justice Eagen join in this dissenting opinion.Congress repudiated this approach by enacting the Omnibus Crime Control and Safe Streets Act of 1968, Act of June 19, 1968, Pub. L. 90-351, 82 Stat. 210, 18 U.S.C. §3501.
Although the appellant in Riggms made but scant mention of delay in arraignment, several members of this Court during oral argument indicated to the Commonwealth’s attorney that Futch might well be involved. Consequently the Commonwealth sought and obtained leave to file a supplemental brief on the application of Futch to an arrest and delay in arraignment occurring in 1969, prior to the effective date of Pa. R. Crim. P. 118 (eff. May 1, 1970). This Court’s refusal to apply the Futch rule in Riggvns can only signify that we there rejected the very argument for retro-activity which is today espoused by the majority.
The initial mistake in this respect was made in Commonwealth v. Tingle, 451 Pa. 241, 301 A. 2d 701 (1973), in which, without discussion, the rule of Futeh was applied to a 1971 arrest. The error of Tingle is thus compounded in the case at bar.
Admittedly the burden on our judicial system would not be serious if the retroactive effect which the majority gives Futch were to be restricted to defendants who have raised the question on post-trial motions or direct appeals which are still pending. This will be the situation if the Court continues, as I believe it should, to limit post-conviction collateral relief to constitutionally based claims, since the rule in Futch is not so mandated. Post-*554conviction relief is so limited in the federal courts and, thus far, has been similarly limited by this Court. See Commonwealth v. Smulek, 446 Pa. 277, 284 A. 2d 763 (1971); Commonwealth v. Lowery, 438 Pa. 89, 263 A. 2d 332 (1970); Commonwealth v. Musser, 437 Pa. 131, 262 A. 2d 678 (1970). But see Commonwealth v. Terenda, 451 Pa. 116, 301 A. 2d 625 (1973), with which Commonwealth v. DuVal, 453 Pa. 205, 307 A. 2d 229 (1973) should be compared.