concur-ing:
I concur in the reversal of Payne’s conviction and affirmance of Kinnard’s. Although I agree with much, perhaps most, of Chief Judge Bazelon’s opinion, there are important differences in approach and emphasis that lead me to state my views separately.
I.
Addict informants present a serious problem of unreliability, for the reasons developed by Judge Bazelon, yet today’s crime problem requires the use of such informants, and court rules should not tamper unduly with the system, sacrificing the security of society without an advance in rights and liberties. The question is, how to retain addict informants, yet keep reasonable rein on them and the problems they present. The best available answer lies in the approach of using the evidence, even without corroboration, but supplying latitude for cross-examination, and cautionary instructions on unreliability when corroboration is lacking on a material aspect of their testimony.
This is the approach put forward in On Lee v. United States, 343 U.S. 747, 72 S.Ct. 967, 96 L.Ed. 1270 (1952) where Justice Jackson said (p. 757, 72 S.Ct. p. 973):
The use of informers, accessories, accomplices, false friends, or any of the other betrayals which are “dirty business” may raise serious questions of credibility. To the extent that they do, a defendant is entitled to broad latitude to probe credibility by cross-examination and to have the issues submitted to the jury with careful instructions.
Therefore, I agree with Chief Judge Bazelon that a defendant is entitled to a “careful” instruction, on request, concerning the unreliability of an informant who is an addict, if in any material aspect that addict-informant’s testimony is not corroborated. That is a sound application of the principle of Fletcher1 and there is no decision of this court to the contrary.
I limit my statement to the necessities of this case, which do not require a ruling beyond the duty to give an instruction on request. But I should be remiss if I did not add my hope that the trial judge would be vigilant and concerned enough ■ to provide such an instruction *578even in the absence of request, the more so in any case when defense trial counsel has been appointed by the court, and does not specialize in criminal law practice.2 Furthermore, the judge would be “well advised” to give such a cautionary instruction,3 particularly when the only corroboration comes from another person, even a police officer, who was involved, whether as participant or surveillant, in the use of undercover arrangements.4 And there may well be a requirement for such an instruction when the circumstances of the case, other than his status as an addict-informant, are such as to cast serious doubt on the witness’s veracity and put it under a cloud.5
II.
The need for this court to rule on the duty to give an instruction on request stems out of the rulings of the trial judge in another context, rulings which interfere with the latitude On Lee cautioned should be available to develop evidence on unreliability.
On cross-examination of Agent Jackson, defense trial counsel,6 having established that it was Roscoe who first mentioned the names of these defendants to the Government agents, sought to cross-examine concerning the unreliability of addict informers.7
The trial judge restricted these questions, ruling that even if Roscoe were an addict,8 “the Court of Appeals has said *579that it would be error to instruct the jury that an addict’s testimony is unreliable simply because he is an addict.” The judge was mistaken in his apprehension of the rule of the decision on which he relied, Godfrey v. United States, 122 U.S.App.D.C. 285, 353 F.2d 456 (1966). Godfrey held it was reversible error to instruct the jury that addicts are inherently perjurious — in a context where some witnesses, who were addicts, were not informers, and were indeed defense witnesses. But a different situation applies to a witness who is both an addict and an informant.
The judge’s mistake in assuming that a special instruction on addict-informants could not be sought was material, for it led him to the error of excluding the question put to Agent Jackson on cross-examination.
Moreover, I think the defense is entitled to bring out before the jury the special unreliability of an informant who is also an addict, whether or not there is an instruction. Indeed, I would feel the trial counsel is entitled to bring out this evidence even in a case where the instruction would not be warranted — because there was corroborating evidence.
III.
Turning to the efforts of defense counsel to introduce evidence of Roscoe’s addiction, he requested that Roscoe bare his arms. On objection, the court said that the use of narcotics was not evidence of a crime. Defense counsel said fresh marks would impeach Roseoe’s testimony that he had not used narcotics recently. The prosecutor said the jury was not qualified to make an inference from its own inspection of his arms. The request was denied.
Next day, trial counsel asked that the court appoint a physician to examine Roscoe’s arms. The court said:
The only thing material about your request [is] whether this man is presently under the influence of narcotics. I think whether he may have needle marks in his arm is a collateral subject and I will deny your motion.
Defense counsel responded that he was not making the request to establish “the fact of his addiction, I accept your Hon- or’s ruling on that yesterday.” In other words defense counsel, being bound by the judge’s prior ruling, that the fact that the informant was an addict was not material, could only make the proffer on a different theory, as showing a contradiction of testimony that impeached the witness. If the prior ruling was correct, this was indeed collateral. But in my view, the prior ruling was wrong. As Judge Bazelon points out, the fact that the informant was an addict is material because it shows his in*580terest in providing information to the police even though it is false. This subject — of interest — is not at all collateral, and can indeed be brought out by extrinsic evidence.9
■Defense counsel had already established his record of error by the trial judge, in his ruling that the status of Roscoe as an addict informant was not material, and in order to present that error he was not obliged to present evidence that Roscoe was an addict; indeed he might have been subjected to censure if he had persisted in the face of the prior ruling and tried to present evidence that the judge had held not material. And in view of the ruling that the evidence was not material, it was obviously not necessary to request an instruction — in a record now devoid of the informant’s addiction — concerning the significance that the jury might properly attach to such addiction if only the judge had recognized the materiality of the informant’s status as an addict.
IV.
As Chief Judge Bazelon points out, there was no corroboration on the issue of entrapment. There is no reason for disagreeing with the ruling of the trial judge that there was an issue of entrapment, which defense was entitled to have the court put to the jury. There was not only the conceded threshold fact that a government agent was given funds to buy narcotics, cf. Hansford v. United States, 112 U.S.App.D.C. 359, 364, 303 F.2d 219, 224 (1962), but in addition the record includes the testimony of Roscoe at trial that Payne did not agree to make the sale on Roscoe’s first request. The fact that Roscoe was an addict-informant, if established, might well have led the jury to conclude that he lied in his subsequent testimony of Payne’s readiness to make the sale.10 This, in my view, provides an overall context in which Payne was entitled to make a showing that Roscoe was an addict as well as an informant, and of the significance of that fact, and would have been entitled to a special cautionary instruction on addict informants. These conclusions establish that it was error to make the rulings identified under II of this opinion.
. Fletcher v. United States, 81 U.S.App.D.C. 306, 158 F.2d 321 (1946).
. Dawkins v. United States, 324 F.2d 521, 523 (9th Cir. 1963).
. Cratty v. United States, 82 U.S.App.D.C. 236, 242, 163 F.2d 844, 850 (1947).
. See Hardy v. United States, 119 U.S.App.D.C. 364, 343 F.2d 233 (1964), cert. denied, 380 U.S. 984, 85 S.Ct. 1353, 14 L.Ed.2d 276 (1965). Judge Washington, dissenting, was of the view that an undercover police officer had such a similarity of interest as the informant that it was not “corroboration” adequate to obviate the requirement of a warning to the jury. Judges Miller and Burger declined to find error but noted that “generally the trial court would be ‘well advised’ to [give the cautionary instruction] and would have been on sounder ground had it given the cautionary instruction here.” The concern is not that a ^police officer is less trustworthy than another witness, but that a police officer in undercover work may not have a sufficient independence of interest from the informant to obviate the desirability of caution concerning the testimony of the informant. The indication, from all three judges in Hardy, of the wisdom of a cautionary ruling concerning the testimony of an informant, notwithstanding the corroboration of a police officer, is in no wise inconsistent with the ruling of Judge Burger that a defendant is not entitled to an instruction that the testimony of a police officer is to be viewed with suspicion, see Bush v. United States, 126 U.S.App.D.C. 174, 375 F.2d 602 (1967). As Bush points out, the testimony of a police officer is not to be viewed with suspicion merely because he is an undercover agent, although the officer is subject to impeachment, cf. Zebedee Hardy v. United States, 118 U.S.App.D.C. 253, 254, 335 F.2d 288, 289, (1964), and to the testing of probing cross-examination, just like any other witness.
. Williamson v. United States, 332 F.2d 123 (5th Cir. 1964).
. These matters relate to cross-examination by counsel for Kinnard, but since he cross-examined prior to counsel for Payne, who was bound by the rulings, the errors are before us on Payne’s appeal.
. The question that led to the ruling was: “Do you have any experience or any knowledge about the reliability of narcotic addicts, insofar as telling the truth or being reliable or being accurate or even caring who they hurt or don’t hurt so long as they are not put in jail?”
While this was objectionable in form as a compound question, its thrust is reasonably plain. It asks concerning the unreliability as informants of addicts, who are enabled by their passing on of information to avoid the consequence they dread of being subject to “cold turkey” withdrawal by being put in jail.
. Although the trial judge at one point said there was no foundation for the question, he receded from that position when defense counsel inquired whether his approach would be permitted if he proffered evidence to show that Roscoe were an addict. The court said that an instruction on addiction would be impermissible, and hence the evidence was inadmissible. This is the pertinent transcript (Tr. 134-135) :
(At the bench)
THE COURT: Judge Pine gave such an instruction about narcotic addicts *579being notoriously unreliable. The case was reversed on that ground. What is your proffer?
COUNSEL FOR KINNARD: My proffer is that we are not asking for an instruction on reliability. We are asking for Iris common experience on reliability.
THE COURT: If it is not admissible as an instruction, it is not admissible as evidence.
THE PROSECUTOR: This officer has not been qualified to give an opinion.
THE COURT: Maybe narcotic addicts are reliable and some are not reliable.
COUNSEL FOR KINNARD: I am not asking for an instruction on narcotic addicts or their reliability. I just want to put it as a fact for a jury to consider.
I am not sure but I think I have seen track marks up and down his arm.
THE PROSECUTOR: I doubt that. I havn’t seen a thing.
THE COURT: I don’t know whether lie has them or doesn’t. You haven’t laid a foundation for this type of testimony.
COUNSEL FOR KINNARD: What foundation would you require? Do you want me to show that Roscoe is an addict?
THE COURT: Even if he were an addict the Court of Appeals has said it would be error to instruct the jury that an addict’s testimony is unreliable simply because he is an addict.
COUNSEL FOR KINNARD: Then I am refrained [sic] from asking any further questions on this subject.
. The judge also said that the request came late, and brought out that counsel for Kin-nard had spoken to Koscoe the previous Sunday. But this fact would not inhibit questioning by counsel for Payne.
. The central entrapment issue is whether the criminal design originated with the Government agent, and the disposition to commit the offense was implanted in the mind of defendant, or whether the defendant was predisposed or ready to commit the offense and was merely afforded an opportunity by the Government agent to do so. Sorrells v. United States, 287 U.S. 435, 53 S.Ct. 210, 77 L.Ed. 413 (1932); Sherman v. United States, 356 U.S. 369, 78 S.Ct. 819, 2 L.Ed.2d 848 (1958).