ORDER
It is hereby Ordered that the earlier vote of this panel denying the Government’s June 18, 1979, petition for rehearing is vacated, and a revised opinion is substituted for the original panel opinion decided April 30, 1979, United States v. Watson, 599 F.2d 1149 (2d Cir. 1979).
The revisions from the original opinion are as follows:.
1. 599 F.2d at 1154. Strike last sentence in third paragraph and in lieu thereof insert the following:
But when the defendant can show substantial actual prejudice, the indictment must be dismissed, for even a legitimate prosecutorial interest is then insufficient to effectuate statute of limitations policies.
2. Add the following three paragraphs after the foregoing insertion:
Ordinarily, when the limitations period has passed, “there is an irrebuttable presumption that a defendant’s right to a fair trial would be prejudiced,” United States v. Marion, supra, 404 U.S. at 322, 92 S.Ct. at 464, and so we bar prosecution — however strong the prosecutorial interest may be. There is a narrow exception to this rule where the prosecution has delayed beyond the limitations period in unsealing a timely indictment. In such a case, we do not give force to the presumption and, if the defendant does not demonstrate actual prejudice, we tolerate delay justified by a legitimate prosecutorial need in unsealing the indictment. But the Government is not relieved of the statutory recognition that actual commencement of prosecution after passage of the limitations period may prejudice the defendant. Accordingly, prosecution should be barred if the defendant can show “substantial, actual prejudice” arising at any time prior to the post-limitations unsealing of an indictment. In such a situation, as in the ordinary case of an untimely indictment, even a strong prosecutorial interest should not toll the statute.
The Government argues that considering prejudice occurring before the limitations period has expired leads to anomalous results. For example, if a sealed indictment is filed one day before the statute has run and unsealed one day after, the indictment can be dismissed if the defendant suffered substantial prejudice even before the sealed indictment was returned. But we do not agree that such an example is an “anomaly” that casts doubt upon our reasoning. What the example does show is that the statute of limitations embodies a strict policy against delay that might prejudice the defendant. It is not “anomalous” that if the sealed indictment were filed one day after the limitations period had expired, the indictment would be dismissed, even though it would not necessarily be dismissed if filed one day earlier. Indeed, in the ordinary case where the indictment is *17never sealed but is returned just outside the limitations period, we do not even inquire into prejudice but simply dismiss the indictment. By contrast, our test for sealed indictments requires dismissal only if the defendant can show substantial; actual prejudice.
It is true that in evaluating claims of prejudice due to alleged unconstitutional pre- and post-indictment delay, we have not considered prejudice to a defendant not arising during or as a result of the period of alleged delay. See United States v. Lai Ming Tanu, 589 F.2d 82, 92 (2d Cir. 1978) (Oakes, J., concurring) (post-indictment delay); United States v. Cheung Kin Ping, 555 F.2d 1069, 1072-73 (2d Cir. 1977) (preindictment delay). But in effectuating the policies of the statute of limitations we cannot limit our concern to prejudice shown clearly to have been caused by the delay after filing. If we are to grant the Government the benefit of a tolling of the limitations period, then we may properly impose a corresponding burden, namely, the risk of dismissal if the defendant has been prejudiced. But the quid pro quo is illusory if we consider only post-filing prejudice, a form of prejudice that the defendant need not show when an ordinary indictment is filed beyond the limitations period.
3. 599 F.2d at 1156 n. 4. Replace footnote with the following:
It is a premise of Judge Friendly’s dissent, as his original opinion set forth, United States v. Watson, 599 F.2d 1149, 1158-59 & n. 1 (2d Cir. 1979) (dissenting opinion), that Muse did not suffer any prejudice by virtue of the lapse of time between the time that the indictment was returned, June 1, 1976, and the time that the indictment was unsealed, late September, 1977; as he put it originally, “Even if we make the charitable assumption that Muse in fact suffered a memory lapse on these items, there is nothing to show it had not occurred before June 1, 1976 ... . ” Id. at 1159. He went on to argue that this “defie[d] the teachings of psychology, as well as common sense.” Id. In support he cited the psychological literature, and particularly Ebbinghaus, relating to “memory declining along an asymptotic curve .... ” Id. at n. 1. His revised dissent in response to the panel’s opinion revised after petition for rehearing remakes the same “asymptotic curve” argument and adds that the district judge doubted whether any memory loss on the part of Muse had occurred and whether, if it had occurred, it did so during the post-limitations or sealing period. We do not think that judicial notice can be taken of the psychological “asymptotic curve” premise on which Judge Friendly’s views are based.. First, it does not sufficiently take into account “retroactive inhibition,” i.e., “interference; inhibition or obliteration of the old by the new,” Redmount, The Psychological Basis of Evidence Practices: Memory, 50 J.Crim.L.C. & P.S. 244, 253-54 (1959). Second, it fails to distinguish between the learning process, perceptual processes and emotional processes, three “distinguishable” processes. Id. Ebbinghaus’s pioneer work as well as the “asymptotic curve” studies which have'confirmed that work relate to learned material, in Ebbinghaus’s own case, nonsense syllables. Id. at n. 29. That is not what we are talking about here.
The additional point now made, that the trial judge said that “one either does or does not remember occurrences of this duration, of this extent for the rest of one’s life” — parenthetically a statement taken from the sentencing minutes — may or may not be an accurate observation, but it is no more than an observation. What we do know is that, at the trial in April, 1978, the key factual issue from Muse’s point of view was whether he had stopped doing business with Diamond and Egister before June 1, 1971, the cutoff date for the statute of limitations, or thereafter. There was no question but what he had done business in 1969 and 1970. His claim was that he had stopped doing so shortly before Diamond’s New Jersey arrest for murder on February 1, 1971, after an argument with Egister and *18Diamond' lasting some fifteen minutes about some “bad merchandise,” that is, “synthetic” heroin. Diamond claimed the conversation occurred shortly after his release on bail on May 16,1971, and Egister claimed that it occurred either in late 1971, “right before the winter started,” shortly after Diamond’s release from jail in May, 1971, or in “early summer.” True, some of Egister’s testimony was tied to dates of Ali fights, but that specifically dealing with Muse was an event which occurred either in March, April, May, or sometime late in 1971, at the time of the Ali-Frazier fight (which was on March 8, 1971), at the time Diamond came out of jail, or right' after he went into jail. Where in short, as here, the exact date of critical events was the very crux of the case (against Muse), the obvious dimming of memories on the part of both prosecution witnesses as well as the defendant that had occurred was in our view necessarily prejudicial. Because we consider that it is impossible to know when that prejudice occurred, we hold as a matter of policy in respect to the statute of limitations, for reasons stated in text, that there must be a dismissal as to Muse.