These four criminal appeals were considered by the court en banc for the purpose of considering an important issue common to each. That issue is whether the statute recently enacted by the Congress, 14 D.C.Code Sec. 305 (Supp. IV, 1971), which mandated the admission into evidence of certain prior convictions of each appellant were he to testify in his own behalf,1 violated appellants' constitutional rights.

*****

* * *We find that the statute, the effective date of which was subsequent to the commission of the offenses for which appellants were tried,2 was, in its retrospective application to the cases before us, an "ex post facto Law" within the prohibition contained in Article I, Section 9, Clause 3 of the Constitution. We remand each case to the District Court for a determination whether, under preexisting law, the prior convictions were properly admitted. In any case where the trial judge finds that the prior conviction evidence should have been excluded, and that the error was not harmless, we order a new trial.

* No. 71-1356.

Appellant Jeffries was tried and convicted by a jury of carrying a pistol without a license. 22 D.C.Code Sec. 3204 (1967). The Government's case consisted of the testimony of the two arresting officers, the pistol, and a certificate that appellant did not have the required license.

Officer Beard testified that appellant's car was pulled over late in the evening of July 28, 1970, because it had a missing tail light and paper license plates that appeared to have been altered. He approached the car from the passenger's side and, upon shining his flashlight into the car's interior, observed the butt of a gun, later discovered to be loaded, protruding from a paper bag on the passenger's side of the transmission hump and within reach of the driver, who, Beard said, was alone in the car. Officer Busker, who approached the car from the driver's side, testified that he also saw no one other than the driver in the vehicle, and that he first saw the pistol when Beard directed his attention to it, after which he arrested appellant. He stated that after arrest appellant repeatedly attempted to return to his own car, whereupon he was subdued and handcuffed.

The defense consisted solely of appellant's own testimony. Contrary to the police testimony, appellant stated that he had as a passenger a friend, one Joe Covington, who left the vehicle just as it was being approached by the two officers. He asserted that, when he asked the officers if he could go after Covington, they refused and said he was resisting arrest. He denied seeing the pistol in his car on the evening of his arrest until Officer Beard recovered it from under the passenger's seat. Defense counsel stated he did not intend to call Covington as a witness. The Government expressed a desire to call him as a rebuttal witness, but decided to proceed without doing so upon discovering his transfer from the nearby jail to a narcotics treatment center.

At a pre-trial hearing on appellant's motion to suppress the pistol,3 the Government announced its intention to impeach appellant with his 1968 robbery conviction should he elect to testify. Defense counsel represented to the court that, 14 D.C.Code Sec. 305 notwithstanding, it should exercise its pre-existing discretion not to permit the impeachment, and that the statute if applied was an ex post facto law. The court stated the new statute made admission of the prior conviction mandatory. At trial defense counsel elicited from appellant on direct examination the fact of his prior conviction; the Government asked the jury to consider this conviction in ascertaining the veracity of appellant's testimony;4 and the trial court instructed the jury that the conviction evidence was admissible solely for consideration in evaluating appellant's credibility and not his guilt of the offense charged.

No. 71-1456.

Appellant Henson was tried and convicted by a jury for violating the federal narcotics laws. 26 U.S.C. Sec. 4704(a) and 21 U.S.C. Sec. 174. The Government's case consisted solely of physical and documentary evidence and testimony of the two female arresting officers, who on the day of apprehension were working in casual clothes in Officer Taylor's private car.

Officer Taylor testified that on the afternoon of August 15, 1970, she and Officer Byrd observed appellant from her car in a doorway ten to fifteen feet away. During their fifteen or twenty minutes of observation, she noted four or five transactions between other persons and appellant, involving the giving of money to appellant, and the provision by appellant of manila envelopes or something from a yellow pouch in exchange. One of two men engaged in one such transaction, who had seen the officers the day before, said "Mod Squad," whereupon appellant looked at the officers and proceeded to a nearby drug store.

Taylor testified that they followed appellant, and that after he entered the store she observed appellant throw the yellow pouch and some money on the floor and move away. Taylor then recovered the money and pouch, which contained twenty-four heroin capsules, and arrested appellant upon Byrd's entry into the store. Outside, the officers detained and searched one John Johnson, who, Taylor said, was a recipient of one of the manila envelopes, but discovered nothing.

Officer Byrd corroborated Taylor's testimony, except that Byrd testified to seeing only two transactions, one with an envelope and one from the pouch, because her position as Taylor's passenger obstructed her view. She also stated that she did not see appellant dispose of anything inside the drug store, having first seen the pouch when Taylor recovered it from the floor.

Prior to presentation of the defense, appellant's counsel requested and received from the Government notice of its intention to impeach both appellant if he testified in his own behalf, and detainee Johnson if he were a defense witness, with the prior conviction of each for violating the Harrison Narcotic Act. 26 U.S.C. Sec. 4074(a). Defense counsel argued that the impeachment statute here in question denied due process of law to those impeached thereunder, and that pre-statute law should control to exclude the prior conviction evidence. The trial judge, apparently relying on the new statute, stated that he would permit the use of the prior convictions, noting that appellant's objection was preserved for appeal.

Three witnesses were presented for the defense in addition to appellant's own testimony. Detainee Johnson, a friend of appellant, admitted having spoken with him as the officers observed, but denied that any transaction took place and stated that he did not see appellant with narcotics or a yellow pouch. On cross-examination Johnson admitted he had been convicted of a Harrision Act violation three days earlier.5 One Linwood Thompson, who knew appellant by sight, was in the drug store, observed appellant's entry closely, and saw the arrest of appellant and the recovery of the pouch. He testified that he did not see appellant throw a pouch or make a throwing gesture, and did not see the pouch or money until the officer picked them up. One James Robinson, an acquaintance of appellant, was also in the drug store at the time and, while he did not notice appellant's actions upon the latter's entry, testified that he did observe appellant thereafter and did not see him with a pouch or making a throwing motion with his arm.

Appellant took the stand in his own defense and, while admitting meeting with a number of people as was observed by the officers, denied (1) that any narcotics transactions took place, (2) receiving any money from these persons, (3) possessing narcotics, envelopes, or the yellow pouch, (4) seeing the officers before they entered the drug store, (5) throwing the pouch or money, and (6) seeing the pouch until the officers picked it up. On cross-examination appellant admitted his 1966 Harrison Act conviction.6 The trial court instructed the jury that the prior convictions of Johnson and appellant were admissible only for purposes of evaluating their credibility, and that appellant's conviction should not be used to infer his guilt of the offense charged.7

No. 71-1491.

Appellant Marshall was convicted by a jury of all counts in a sevencount indictment arising out of the shooting of one woman and the murder of another in the early morning hours of June 21, 1969.8 The Government's case as to the surviving victim, Shirlyn Young, included her identification of appellant; its case as to the murder victim was entirely circumstantial.

Victim Young testified that she was able to see her assailant's face during his fifteen minutes in her apartment, and that he then was wearing a yellow shirt, green pants, a round white hat, and black shoes. She stated that she did not identify the assailant in any of the three photographic arrays-none of which included appellant-shown to her in the hospital to which she was taken after being shot but, having earlier made an in-court identification of appellant, said that she did identify appellant at a photographic lineup at her home approximately three weeks after the shooting. Her neighbor testified to seeing, at about the time of the shooting, a man with a gun wearing a yellow shirt and green pants moving away from the building in which Young lived. The neighbor stated that appellant very much resembled that man.

A neighbor, who lived next to the murder victim's apartment building and a few blocks from that of victim Young's, testified that while sitting on the steps of her own building she saw the murder victim enter the latter's building with a man, heard signs of fighting and gunshots approximately five minutes later, and shortly thereafter saw a man in the murder victim's apartment wearing a white hat who seemed to be the man that earlier had entered the building with the victim. The neighbor said the man with the hat later left the building, and that he had approximately the same complexion, build and height of appellant. The two other persons sitting on the steps at the time corroborated this story, including appellant's general physical resemblance to the individual seen leaving the victim's building. One of these witnesses added that the departing man was carrying a yellow jacket. The murder victim's roommate testified to having earlier played cards with the victim and others in their room; the room was cleaned after all had departed, the roommate noting no cigarettes were left in the ashtray, and that the victim had none. A cigarette was found in the ashtray after the murder; other testimony revealed that appellant smoked, as was observed during his arrest in New York.

The day after the two incidents, appellant, who was wearing green pants and a white cap, was involved in an argument at a gas station. The station manager's complaint to the police of appellant's threatening him with a gun resulted in police seizure of the gun from under the driver's seat of the car appellant was driving. Unchallenged testimony from a ballistics expert established that the two unmutilated bullets recovered, one from the body of each victim, were fired from the revolver seized at the gas station.9

At the pretrial hearing on appellant's motion to suppress the revolver, defense counsel raised the question whether, should appellant elect to testify in his own behalf, the court would permit his impeachment by prior convictions. The Government proffered appellant's 1965 conviction for assault with intent to commit grand larceny, and his 1970 conviction for armed robbery. The trial judge stated, apparently with reference to the new impeachment statute, that the matter was no longer subject to question. Defense counsel objected, and said in view of the admissibility of the convictions he would recommend to appellant that he not testify. At trial counsel again sought a ruling on the admissibility of appellant's prior convictions. The trial judge stated the admissibility of both convictions was mandated by the new statute, while advising appellant of his right to testify. Appellant did not testify.

The defense was alibi and mistaken identity.10 Appellant's brother testified that appellant was home at the time of the offenses charged. An acquaintance of appellant's testified that the day before appellant was arrested at the gas station, and after the shootings with which he was charged, a third party who knew appellant approached him and the witness, and sold appellant a gun which looked to be the same as the one used to shoot the two victims. A number of witnesses were also brought forward to support the theory that someone other than appellant committed the offense, see note 10 supra.11

No. 71-1497.

Appellant Brown was convicted by a jury of unlawful possession of stolen mail matter-specifically, a civil service retirement check payable to one Frances M. Wright-in violation of 18 U.S.C. Sec. 1708. The prosecution was directed toward establishing that appellant knew the check in his possession was stolen. The Government's theory of the case was that appellant, in league with others, stole the check in question and forged the payee's endorsement. It was stipulated that the endorsement was not in appellant's handwriting.

Testimony elicited by the Government revealed that the check was mailed to the payee on April 15, 1970, but that her mailbox was broken into on April 17 and that she never received the check. Appellant's neighbor, Miss Gray, a Post Office employee, testified that on April 22 appellant asked her to cash the check for him while she was at work. She stated appellant gave no reason for his request, and that he apparently had his own bank account, since the week before he had written a check payable to her as a loan. Circumstances led her to discuss the request with her supervisor. She was advised to, and did, meet with appellant at noon as he had arranged, and returned the check, whereupon a postal inspector arrested appellant and seized the check.

Over objection, the trial judge ruled the inspector qualified as an expert in stolen checks after a voir dire conducted outside the presence of the jury. The inspector revealed that it was not uncommon for one person to steal the check, another to forge the endorsement, and a third to cash it. He gave an example from his experience wherein, prior to an attempt to purchase his merchandise by a check with a forged endorsement, a merchant was alerted by telephone that the caller was sending a purchaser who would present the caller's check, and was asked to cash the check.12

Appellant was convicted of false pretenses in 1959, and of forgery in both 1964 and 1966. Believing the Government would attempt to use these convictions to impeach appellant were he to testify, appellant filed a pretrial motion contending that such an attempt would violate his constitutional rights. The trial judge denied the motion in reliance upon the new impeachment statute; and he informed appellant that the convictions would be admissible for impeachment purposes if appellant took the stand. Appellant chose to testify.

Appellant's version had it that he was approached in early April by a person representing himself to be a "Mr. Wright," who was referred to appellant by his neighbor, Miss Gray. Mr. Wright asked appellant to perform certain plumbing repairs on two fire-damaged houses. After making an estimate, appellant asked for an advance to purchase the necessary materials. On April 20, Mr. Wright met with appellant, endorsed the check in question in appellant's presence, and gave him the check and a list of supplies to purchase at the Apex Plumbing Company, where Mr. Wright said he was known. The aforementioned stipulation also noted that the list was not in appellant's handwriting, and that both the list and the forged endorsement were in the same handwriting.

Appellant went to Apex and presented the list and check. Apex refused to cash the check. Appellant called Mr. Wright; the Apex manager spoke to him, but still would not cash the check. On April 22, appellant asked his neighbor to cash the check, and, in closing, it was argued to the jury in his behalf that he did not have a checking account. Appellant stated he did not know the check was stolen until he was arrested with the check, as well as the list of plumbing supplies, in his possession.

Defense witnesses included the Apex manager, who remembered appellant presenting the check and list of supplies and the telephone call with Mr. Wright. A number of witnesses called attested that, despite appellant's affliction with polio, he did work as a plumber. And a Secret Service Agent, to whom appellant was turned over after his arrest, presented a statement then made by appellant corroborative of appellant's testimony.

Cross-examination revealed that circumstances prevented appellant from obtaining Mr. Wright and one "Duck"-a helper appellant asked to assist appellant in the Wright job-as defense witnesses. Appellant admitted his three prior convictions earlier mentioned, while each time adding that he pleaded guilty to the charges. At the close of trial, the judge instructed the jury to consider those convictions only to assess appellant's credibility.13

Prior to the effective date of the new impeachment statute, see note 2, supra, its predecessor provided that the fact of a witness' prior conviction "may be given in evidence to affect his credibility," 14 D.C.Code Sec. 305 (1967) (Emphasis added). In 1965 we interpreted that language as empowering the trial judge to admit the prior convictions of a defendant testifying in his own behalf, but not as invariably requiring such admission. It was our view that the language used by Congress did not, either in terms or intention, negate the existence of a discretionary power more likely to further the achievement of the goal of a criminal trial, i.e., "the disposition of the charge in accordance with the truth." Luck v. United States, 121 U.S.App.D.C. 151, 348 F.2d 763, 769 (1965).

With this objective in mind, the principal consideration in the exercise of that discretion would be whether "the prejudicial effect of impeachment far outweighs the probative relevance of the prior conviction to the issue of credibility." Id., at 768. And our apprehension embraced not only the possibility that admission of prior convictions would have an improper influence upon the jury's deliberations upon a defendant's guilt, but also that a defendant might perceive the same possibility and be thereby deterred from giving testimony in his behalf. In such situations, we thought a trial judge should be able to resolve the question of whether the pursuit of truth would better be served by permitting the defendant to testify without fear of impeachment.

In Luck we identified various factors we thought might appropriately inform the decision of a trial judge on this question; and in Gordon v. United States, 127 U.S.App.D.C. 343, 383 F.2d 936 (1967), cert. denied, 390 U.S. 1029, 88 S.Ct. 1421, 20 L.Ed.2d 287 (1968), we explored in detail the proper implementation of Luck. Judge (now Chief Justice) Burger, writing for the court in Gordon, noted that the responsibility for raising the question of the admissibility of prior convictions was the defendant's, and that he also bore the burden of persuading the trial judge that his prior convictions should be excluded. But, once raised, the defendant was entitled to an on-the-record consideration of the issue; and indeed it was suggested that in some cases a determination could best be made only following a non-jury hearing wherein a defendant would testify and be cross-examined, bringing into sharper relief the nature of the problem posed by the impeachment in question.

The new statute provides that, if a prior conviction meets the criteria set forth therein, it "shall be admitted if offered," see note 1 supra, (Emphasis added). It replaces the time-honored discretion of trial judges, in ruling on questions of admissibility of evidence, to weigh probativeness against prejudiciality-a discretion which we found Congress preserved in the earlier statute-with a rigid legislative judgment as to which prior convictions must be admitted for impeachment purposes. We think the availability to a criminal defendant of the exercise of judicial discretion in this matter invests him with significant and substantial rights which are nullified by the legislative scheme enacted to replace it. Accordingly, to the extent that that scheme is applied in trials for offenses committed before its effective date, the statute in which it is embodied is condemned as an ex post facto law.

It is generally accepted that laws which make acts criminal which, when done, were not criminal, or those which increase the seriousness of, or provide a greater punishment for, criminal acts over that which obtained when the acts were committed, fall within the constitutional condemnation as being ex post facto.14 Conversely, changes in procedure customarily are not generally treated as ex post facto. See, e.g., Frisby v. United States, 38 App.D.C. 22, 25 (1912). As Frisby noted, however, it has been clear, beginning with the first case in which the Supreme Court was called upon to construe the clause, that procedural changes can be ex post facto, id., at 25; and that those changes include alterations in the rules governing the admissibility of evidence.

The Supreme Court's initial pronouncement on the ex post facto clause held that an enactment of the Connecticut legislature setting aside a probate decree was not prohibited by the clause because the enactment did not relate to penal matters. Calder v. Bull, 3 U.S. (3 Dall.) 269, 1 L.Ed. 648 (1798). In so limiting the scope of the clause the Court also set forth, through Mr. Justice Chase, what laws it thought to be within the prohibition, and those included:

. . . Every law that alters the legal rules of evidence, and receives less or different testimony than the law required at the time of the commission of the offence, in order to convict the offender . . . Id. at 273.

In Cummings v. Missouri, 71 U.S. (4 Wall.) 277, 18 L.Ed. 356 (1866), the Court struck down as ex post facto the clause in the Missouri Constitution-there applied to a Catholic priest-punishing those who held office and did not take the loyalty oath constitutionally required of the clergy and others which stated, inter alia, that the taker had never manifested support for the confederacy. The Court in part characterized the clauses in question as operating to "subvert the presumptions of innocence, and alter the rules of evidence," theretofore thought to have been fundamental. Id. at 328.

Kring v. Missouri, 107 U.S. 221, 2 S. Ct. 443, 27 L.Ed. 506 (1882), similarly invalidated a Missouri constitutional provision which had been interpreted to abrogate pre-existing law that made judgment and sentence for second degree murder, where first degree murder had been charged, an acquittal of the first degree charge. The Court held that

. . . the Constitution of Missouri so changes the rule of evidence, that what was conclusive evidence of innocence of the higher grade of murder when the crime was committed . . is not received as evidence at all, or, if received, is given no weight in behalf of the offender. . . . Id. at 228, 2 S.Ct. at 449.

Our own court held long ago in Frisby, supra, that a statute repealing an earlier enactment prohibiting the use as evidence against a criminal defendant of his pleadings in another judicial proceeding was ex post facto in nature, since it rendered admissible a forged document which was the sole proof of the commission of the offense charged. Id. at 27. And earlier this year we held in United States v. Williams, 154 U.S.App.D.C. 244, 475 F.2d 355 (1973), that a provision of the D.C. Court Reform and Criminal Procedure Act, which placed upon the defendant the burden of affirmatively establishing an insanity defense by a preponderance of the evidence, was invalid as an ex post facto law when applied to an offense committed before the effective date of the statute. See also United States v. Gilbert, No. 71-1687, decided without opinion but citing Williams.

In those cases in which the Supreme Court held the challenged procedural change not to be ex post facto, it nevertheless acknowledged that such changes could on occasion fall within the prohibition. Hopt v. Utah, 110 U.S. 574, 4 S.Ct. 202, 28 L.Ed. 262 (1884) (upheld repealer of statute preventing convicted felons from being witnesses); Thompson v. Missouri, 171 U.S. 380, 18 S.Ct. 922, 43 L.Ed. 204 (1898) (upheld statute which made admissible previously excluded genuine examples of defendant's handwriting); Beazell v. Ohio, 269 U.S. 167, 46 S.Ct. 68, 70 L.Ed. 216 (1925) (upheld statute which provided for separate trial for good cause shown, rather than previously accorded right to separate trial).15

What is, or is not, a procedural change amounting to an ex post facto law depends, then, upon its effect on the accused. The effect has been variously stated. Kring, supra, quoted with approval from United States v. Hall, 2 Wash. C.C. 366, that a law is ex post facto which "'in relation to the offence, or its consequences, alters the situation of a party to his disadvantage . . . takes away or impairs the defence which the law had provided the defendant"' at the time of the offense. 107 U.S. at 228-229, 2 S. Ct. at 449-450. (Emphasis added.) Kring also held that a law of procedure will be ex post facto where it takes away "any substantial right which the law gave the defendant at the time to which his guilt relates," id. at 232, 2 S.Ct. at 453, and this latter formulation appears consistently in the later cases, as to the other phrases with less consistency. See Hopt, supra, 110 U.S. at 589, 4 S.Ct. 202; Thompson v. Utah, 170 U.S. 343, 352, 18 S.Ct. 620, 42 L.Ed. 1061 (1898); Thompson v. Missouri, supra, 171 U.S. at 384, and at 388, 18 S.Ct. 922 ("substantial guarantees"); Beazell, supra, 269 U.S. at 171, 46 S.Ct. 68; Frisby, supra, 38 App.D.C. at 25.

While the question before us may thus be cast in the mold of whether appellants have been deprived of a "substantial right," it is evident that:

Just what alterations of procedure will be held to be of sufficient moment to transgress the constitutional prohibition cannot be embraced within a formula or stated in a general proposition. The distinction is one of degree . . . .Beazell, supra, at 171, 46 S.Ct. at 69.

The right we are here dealing with is the right of an accused to invoke the exercise of the trial judge's discretion, informed by the factors set forth illustratively in Luck and Gordon, supra, in ruling on the admissibility of the accused's prior convictions. Whether the retrospective application of the new impeachment statute worked a deprivation of a substantial right depends upon the nature and degree of the disadvantage to the accused imposed by the substitution of a fixed legislative judgment for a judge's informed discretion on this issue. We conclude that the particularized consideration which this claim of an accused has heretofore received is a protection of the magnitude necessary to involve the ex post facto clause.16

The prejudice against which the Luck rule was designed to protect an accused-the effect of prior convictions in creating an inference of guilt rather than in merely evaluating the accused's credibility-may be overborne by the governmental interest in admitting the evidence for impeachment purposes, but that prejudice exists nonetheless. See Spencer v. Texas, 385 U.S. 554, 561, 87 S.Ct. 648, 17 L.Ed.2d 606 (1967); Dixon v. United States, 287 A.2d 89, 93 (D.C.C.A.1972). And it is especially noticeable in those cases one might posit where, absent the new statute, the trial judge might have excluded otherwise admissible prior convictions. In those circumstances Congress presumably may have concluded that the governmental interest should in any event prevail-but that is a judgment which deprives the accused of a substantial right in two significant ways, whether or not the judgment is otherwise constitutionally permissible.

First, the prejudice flowing from the admission of convictions for past offenses, which we need not belabor here, inevitably operates to dilute the impact upon the jury of the accused's testimony as to his innocence of the offense for which he is presently on trial. Luck, supra, 348 F.2d at 768. This possibility remains despite the issuance of limiting instructions. See Bruton v. United States, 391 U.S. 123, 88 S.Ct. 1620, 20 L.Ed.2d 476 (1968). As such it may make the Government's burden of proof less onerous which-whatever effect it may have on the constitutional requirement that the Government bear the burden of proof beyond a reasonable doubt, In re Winship, 397 U.S. 358, 90 S.Ct. 1068, 25 L.Ed.2d 368 (1970)-would in turn result in a conviction on "less . . . testimony than the law required at the time of the commission of the offence . . . ." Calder, supra, at 273. See also Cummings, supra, at 326. It was the absence of just such an effect that the Court pointed to in upholding the challenged statutes in Hopt and Thompson v. Missouri.17

Second, the new statute may-as it perhaps did in the case of appellant Marshall, especially since he faced a possible death sentence-operate in such a manner that it "takes away or impairs the defence which the law had provided the defendant," Kring, supra, at 229, 2 S.Ct. at 450. The defense at issue here is the testimony of the accused himself; and, while he had the right to testify in his own behalf, it may nonetheless be a significantly diluted right if the risk of the above-described prejudice flowing from the mandatory admission of his prior convictions is so high that he is deterred from invoking that right. See United States v. McCord, 137 U.S.App.D.C. 5, 420 F.2d 255, 257 (1969); Kalven & Zeisel, The American Jury 146-47 (1966). Cf. Luck, supra, 348 F.2d at 769; Gordon, supra, 383 F.2d at 940. And to the extent this deterrence is determinative in a situation where an accused's testimony is his only defense, its effect is self-evident even if it may not be unconstitutional. Cf. McGautha v. California, 402 U.S. 183, 91 S.Ct. 1454, 28 L.Ed.2d 711 (1971).18

When viewed as a statute which may not only lessen the amount of proof required for conviction, but also as one which may in practical effect impair or wholly take away a defense that might, absent the new statute, have been available, it is clear that statute potentially "alters the situation to the disadvantage of the defendant" within the meaning of the ex post facto clause as construed by the Supreme Court. Accordingly, the statute is unconstitutional in its retroactive application to the cases before us.19

In each of these cases appellants raised in timely fashion the question of whether, should they testify in their own behalf, their prior convictions would be admissible. In each instance the trial judge considered himself precluded by the new statute from bringing to bear on that question the discretionary elements which might conceivably have resulted in a ruling of exclusion. Jeffries, Henson and Brown each elected to testify, while maintaining, on various constitutional grounds, their objections to the new statute and its application to them. Marshall elected not to testify on the advice of his attorney, of which advice the judge knew in advance of his ruling. See Williams v. United States, 129 U.S.App.D.C. 322, 394 F.2d 957, cert. denied, 393 U.S. 984, 89 S.Ct. 457, 21 L.Ed.2d 445 (1968).

We cannot say, in view of the "inescapable remoteness of appellate review," Luck, supra, 348 F.2d at 769, how an informed discretion would have been exercised, nor do we think it appropriate for us to volunteer any views as to how it should have been exercised or whether the failure to exercise it was harmless error. Those are matters more properly to be determined in the first instance by the District Court on remand.20

The convictions appealed from are affirmed in all respects except that the cases are remanded to the District Court for the purpose of enabling that court to consider, free of the constraints of the statute in question, whether impeachment by prior conviction should have been permitted. In any case where the court concludes that it should not have been, and where the court does not find the error to have been harmless, it shall afford a new trial.

It is so ordered.

BAZELON, Chief Judge, concurring in part and dissenting in part:

I agree with the Court that 14 D.C.Code Sec. 305, as applied to defendants whose offenses were committed prior to its effective date, is an ex post facto law. I concur, therefore, in remanding the cases to allow the District Court to consider, under the Luck rule,1 whether evidence of prior convictions should have been admitted.

My disagreement with the Court concerns only its holding in the Henson case, contained in footnote six of the Court's opinion, that it was harmless error in the circumstances of the case for the trial court to fail to give, sua sponte, an immediate cautionary instruction regarding the limited purpose for which evidence of former convictions, may be used. The Court says that, in any event, it does not find this omission cognizable as plain error.

There is no question, of course, that if evidence of Henson's prior Harrison Act conviction was admissible at all, it was admissible only for the purpose of evaluating the credibility of his testimony in his own behalf. Nor is there any question that such evidence, when admitted, can have a significant prejudicial effect, particularly when the former conviction was for an offense similar to that for which the defendant is being tried. When it decides to admit such evidence, the trial court should be aware, without prompting of counsel, of the special dangers posed to the fairness of the trial. It is, in my view, incumbent upon the court to take whatever steps necessary to mitigate these dangers as much as possible. And while the immediate cautionary charge is, I grant, a fragile reed upon which to rely, it is the best device available for reducing the possible prejudicial effects of prior conviction evidence.

Despite its erosion in subsequent cases,2 I would adhere to the rule stated in McClain v. United States:3

We would hold that whenever evidence is admitted only for a limited purpose, it is plain error, in the absence of manifest waiver, to omit an immediate cautioning instruction. The danger of prejudicial effect from such evidence is so great that only an immediate and contemporaneous instruction can be considered sufficient to protect defendants. As long as we continue to have rules of evidence which admit testimony for some purposes but not for others, we must guard against its misuse by the jury.

Moreover, I cannot agree that the trial court's failure to abide by this rule was, in the Henson case, harmless error. The Court recognizes the "inescapable remoteness of appellate review;"4 yet it would attempt to estimate the quantum of benefit that might have been derived had the immediate instruction been given in this case. The Court may well be correct in its conclusion that, in fact, the quantum of benefit would have been negligible. But, of course, its conclusion rests entirely and necessarily on speculation, the premises of which are uncertain at best.

Such speculation may often be a necessary, if unfortunate, aspect of the appellate function, and I have no doubt that the harmless error rule may be appropriately applied, particularly when an error concerns matters peripheral to the central issues in a case. Here, however, I think the Court's enthusiasm for the harmless error rule is altogether misguided. The requirement of an immediate cautionary instruction is intended to mitigate a substantial danger to the fairness and accuracy of the guilt-determining process. In my view, it profits neither the cause of judicial efficiency nor what is more important, the administration of justice, to announce a rule and then to undercut it by repeatedly pronouncing its violation harmless. Reluctant as we are to "overload the system" by requiring that a case be retried, by refusing to do so we may well defeat the goal for which we strive. It is, I think, precisely our readiness to find an error harmless that makes it likely to recur and thus to be again and again the subject of our review. Adherence to a straightforward rule may do much to ensure consistency in our administration of justice and, in the long run, to promote its efficiency.

With the exception of this point, I concur in the judgments and the opinion of the Court.