This is an appeal following appellant’s conviction for possession of a short-barreled shotgun that was unregistered and without serial number, in violation of 26 U.S.C. §§ 5861, 5871, and possession of cocaine, heroin, and marijuana with intent to distribute, in violation of 21 U.S.C. § 841(a). The central issue is whether there was reversible error because the trial court refused a special instruction concerning the particular interest of the principal prosecution witness as accomplice or informant. We affirm.
I. STATEMENT OF FACTS
Authorized by a search warrant, Federal agents 1 and metropolitan police officers forced entrance, on November 24, 1971, into the then unoccupied apartment B-4 at 4920 A. Street, S.E. During a lengthy search, officers discovered a short-barreled shotgun with a pistol grip underneath and to the rear of a stereo cabinet located in the living room. They also seized $3000 in cash “from the sofa cushions located in the front room.” Throughout the apartment were found various articles commonly used in adulterating and packaging narcotics for sale, including measuring spoons, strainers, aluminum foil, glassine bags, two playing cards and several cans of dextrose. Most important was the discovery of significant quantities of illicit drugs. A large amount of cocaine was removed from the kitchen table; a somewhat smaller batch of cocaine was found underneath a bed; an envelope containing marijuana was found on a nightstand; and in a second bedroom, heroin was found both on the floor and in a coat hanging in the closet.
Appellant was the lessee of the A Street apartment throughout 1971. From some point in late September until October 18, the apartment was occupied, with appellant’s permission, by Roland Henry and Faith Elaine Wise, both then fugitives from justice.
At trial the Government presented the items seized in the apartment, testimony of the Government’s expert as to the high concentration and “street value” of the confiscated drugs (contradicted in part by appellant’s witness), and the testimony of Ms. Wise.
Faith Wise testified that while she and Roland Henry occupied the apartment appellant visited daily to socialize, to carry out his shopping for the couple, and to “snort” drugs with them. At no time did she see a sawed-off shotgun in the apartment.
As to the drugs found in the apartment she testified: On October 16, 1971, she and Mr. Henry acquired a half kilogram of heroin and an eighth of a kilogram of cocaine. When they departed on the 18th, they took $120,000 in cash and left behind no money, but five “pieces” 2 of heroin and three “pieces” of cocaine for appellant to sell, under an understanding that some of the profits were to be turned over to Henry, and appellant was to keep the rest.3
Appellant admitted he had rented the A Street apartment. But he insisted a flood forced him to move out in July, 1971, and that he subsequently never spent any evenings there. He conceded that he had left all his furniture at the *115apartment and had returned frequently to change his clothing.
Appellant also testified as follows: Henry and Ms. Wise stayed at appellant’s apartment from September until the end of October, 1971. Henry contributed money for rent while he occupied the apartment. Appellant went to the apartment one or two times per week during Henry’s stay. He admitted using cocaine with Henry and Ms. Wise and seeing a large quantity of drugs. He denied, however, that any narcotics were left with him; denied having seen the sawed-off shotgun; and denied ownership of both the coat in which the heroin was found and the narcotics paraphenalia. He did state that he had returned to the apartment on “an average of twice a week” after Henry and Ms. Wise had left (Tr. 389); but he testified that he thought that Henry and Wise were going to return to the apartment, so he left everything as it was when they went.
II. SUFFICIENCY OF INQUIRY INTO AND INSTRUCTIONS ON SPECIAL INTEREST OF PROSECUTION WITNESS
A. Trial Court Developments
1. Testimony of prosecution witness
It was brought out at appellant’s trial that Ms. Wise, after leaving appellant’s apartment, was arrested on November 1, 1971, in Albuquerque, New Mexico, and charged with possession of heroin, cocaine, marijuana, methadone, and demer01. She pleaded guilty to one count of possession of marijuana with intent to distribute, and received a sentence for five years’ imprisonment. She testified that she made no agreements with anyone at the time in order to limit her liability to the offense of possession of marijuana. She further testified, against the advice of her attorney, about her criminal involvement in at least two additional drug-related offenses; but asserted that she had been a party to no “promises, guarantees, or understandings” with the United States Attorney’s office. She has not been prosecuted for either of these offenses, according to the representations of both counsel at oral argument, which we accept.4
2. Denial of request for special instruction
At the close of testimony, government counsel requested that the judge give an informant’s instruction with respect to Ms. Wise. This request was denied. It was renewed with greater vigor by defense counsel.5 The court again refused to give the requested instruction. It stated that Ms. Wise was “not an informant, she’s a plain witness. . She is not an accomplice.”6
*1163. Summation of defense counsel
In summation to the jury, defense counsel stressed that prosecution witness Wise was permitted to plead to the relatively minor offense of possession of marijuana and had two cases pending in which she might obtain immunity, and argued this was important to consider as showing bias in her testimony.7
4. Credibility instruction to jury
The trial judge gave a conventional instruction to the jury on credibility, stating that they were the sole judges of the credibility of witnesses, and advising them that they might consider any matter bearing on credibility of a witness and of the testimony given, including whether the witness had any interest in the outcome of the case.8
B. Discussion of Legal Issues
In our view a fair trial was provided as to the issue of a possible special interest of the principal prosecution witness arising out of her. involvement in this crime and other crimes. Defense counsel was given latitude to adduce evidence pertinent to these issues, to cross-examine the prosecution witness, and to present argument to the jury on the issue of possible witness interest and bias. The trial court charged the jury that in assessing the credibility of testimony it could take into account the interest of any witness. While the judge had latitude to give special guidance on possible interest, in the circumstances of this case we see no basis for reversal because the trial judge limited himself to the general instruction on credibility and interest.
1. Instructions concerning effect of witness’s interest on credibility — in general
Before we consider whether and to what extent there is a requirement for special instructions on interest of witnesses, it is important to emphasize the undoubted latitude of counsel to adduce evidence pertinent to interest and to argue to the jury its impact on credibility.
Alford v. United States, 282 U.S. 687, 51 S.Ct. 218, 75 L.Ed. 624 (1931), sustained the right of defense counsel to show that the prosecution’s witness was in Federal custody, by cross-examination which, while respecting the bounds against questioning merely to harass, annoy or humiliate, was conducted in or*117der “to show by such facts as proper cross-examination might develop, that his testimony was biased because given under promise or expectation of immunity” or that “his testimony was affected by fear or favor growing out of his detention.” 282 U.S. at 693, 51 S.Ct. at 220. See also District of Columbia v. Clawans, 300 U.S. 617, 630, 57 S.Ct. 660, 81 L.Ed. 843 (1937).9
In Davis v. Alaska, 415 U.S. 308, 94 S.Ct. 1105, 39 L.Ed.2d 347 (1974), the Supreme Court held that the Confrontation Clause requires that a defendant be allowed to cross-examine a prosecution witness as to possible bias deriving from the witness’s probationary status as a juvenile delinquent, despite a state statute directing that such status remain confidential.
The availability of vigorous cross-examination is significant context for validating the use and testimony of accomplices and secret informers as a necessary means of coping with covert criminality. On Lee v. United States, 343 U.S. 747, 757, 72 S.Ct. 967, 96 L.Ed. 1270 (1950),10 Hoffa v. United States, 385 U.S. 293, 311, 87 S.Ct. 408, 17 L.Ed.2d 374 (1966).11 Counsel has reasonable latitude not only in questioning witnesses but in argument to the jury where, provided he abstains from unjustified character assassination and vilification, he may put his view of the veracity of witnesses, and the character and weight of their testimony.12
The role of the judge in giving instructions to the jury, sharply distinguished as it is from the adversarial role of counsel, brings different considerations into play. In general, the courts of this country have receded from their historic common law powers of latitude in commenting on the evidence. In furtherance of the predominant role of the jury in finding the facts, and in order to avoid the problems of unfairness associated with singling out particular witnesses or classes of witnesses, and with giving emphasis or undue prominence that unduly favors one party, courts frequently confine themselves to credibility instructions that are general in nature.13 Even in the Federal courts, which have never yielded the right to comment on the evidence, there has been some curtailment of commentary in the wake of rulings disapproving instances of judicial comment.14
*118This aspect of the law of trials involves a number of considerations — the role of judge and jury, the difference between rulings of law and findings of fact, and the overall composite of a fair trial. Even a Federal judge must take care lest his instruction over-steer members of a jury in fact, notwithstanding a general disclaimer that theirs is the fact function.15 And although a Federal judge necessarily draws on his personal experiences when a case is tried to a court, as in assessment of demeanor, he does not have free range to translate these into instructions for the jury, as appears from Quercia v. United States, 289 U.S. 466, 53 S.Ct. 698, 77 L.Ed. 1321 (1933).16 What seems evident to one judge, based on his experience, may be questioned by another; and instructions to the jury, which deal with the law, are properly confined to propositions that reflect the wisdom of the community — an instance of judicial notice translated into an instruction.17
This is, then, an area of the law where the baseline of doctrine calls for affirmance of a judge who confines himself to general instructions on credibility as affected by witnesses’ interest, and to providing in that way a context that supports the materiality of efforts of counsel to elicit evidence and present argument. Defendant then has the burden of supporting any claim that special instructions are imperative on the ground that there is justification for this exception in the need to assure a fair trial. This brings us to the doctrines on special instructions for accomplices and informers.
2. Withholding accomplice instruction
Appellant assigns as error the failure of the trial judge to instruct the jury that Ms. Wise, who by her own admission was to share in the proceeds of appellant’s sales of narcotics, was his accomplice, and that being an accomplice her testimony should be “received with caution and scrutinized with care.”
Although a conviction may rest solely on the uncorroborated testimony of an accomplice,18 accomplice testimony is inherently less reliable than that of other witnesses. In some jurisdictions there is an absolute prohibition, typically set by statute, against conviction on the uncorroborated testimony of an accomplice. More generally the rulings permit a conviction on this basis provided a cautionary instruction is given. No fixed form has been set, and the wording of the caution varies somewhat in the cases. A conventional and approved form runs: “The testimony of an accomplice should be received with caution [or suspicion] and scrutinized with care.” 19 When such an instruction *119is requested and the testimony of the accomplice is uncorroborated, it is reversible error to deny such an instruction20 As the authorities cited show, this is the doctrine announced both by our court, with precedents from the days when it was still expositor of the common law of the District of Columbia, and by other Federal courts.
As to the basis of the doctrine, there is language in some decisions suggesting that its root lies in the witness’s own impairment by his self-incrimination.21 This kind of rationale harks back to old doctrines that made felons, and the accused, incompetent as witnesses,22 but has little force today. In terms of current realities, the thought should be turned the other way around, for as Judge Brown has effectively noted, an accomplice’s own “confession of the soul” carries a “ring of truth” and it is, indeed, this circumstance that impels the court to caution the jury of the dangers of accomplice testimony.23 The need for careful scrutiny of an uncorroborated accomplice reflects the danger, underscored by experience, that he may be giving a false account to secure lenient treatment.24
The prospect of immunity or leniency “is usually denied, and may not exist; but its existence is always suspected.” 25 And so even though there is no testimony in the particular record that the accomplice is testifying out of a prospect of leniency or immunity, the probability that accomplices as a class are likely to do so warrants the cautionary instruction as a reflection of general judicial experience — when the accomplice is uncorroborated.
Opinion is split as to whether it is “plain error” to fail to give the accomplice instruction even in the absence of a request.26 The present case is marginal, for there was no request by defense counsel for an accomplice instruction. The District Judge did volunteer his thinking that Ms. Wise was not an accomplice, but his comment was in course of considering a request for an informant’s instruction. Appellant says this comment rendered futile any explicit request for an accomplice instruction; but when a contention is seriously urged by an attorney he is likely, even in the face of preliminary resistance, to put it, with all propriety, that he would like to be heard on the subject. However, since *120the matter was at least addressed by the trial judge, we hesitate to affirm on the ground of failure to make a request, which is required in order to assure his consideration. It suffices to dispose of this case, as will presently appear, that in our view there was sufficient corroboration to avoid the need for an accomplice instruction.
Presence of corroboration
Where there is material corroboration, the law is that failure to give a cautionary accomplice instruction is not error — whether requested27 or not.28 This puts the matter to the jury with the general instruction on credibility of witnesses. Otherwise, a cautionary instruction against the accomplice tilts against believing the accomplice even when he has been largely corroborated. The matter is one for the trial judge's informed discretion, although prudence points toward giving an instruction whenever there is doubt as to the sufficiency of the corroboration. The extent of corroborative evidence required to alleviate the need for a cautionary instruction cannot be measured with mathematical precision. Not as much evidence is required as for the harmless error rule, for evidence that by itself may be insufficient to convict may nonetheless enable the trial judge to ensure that fairness is sufficiently achieved with the general instruction on credibility of witnesses.
In sum, the guidance that the law requires for the jury is a practical adjustment. When there is no corroboration, the problem of perjury looms large and warrants a judicial exposition on the frailties of accomplice testimony. When the accomplice’s testimony is corroborated in material degree, there is no significant special problem of perjury; the persisting problem of perjury in fact in the specific case is like that which besets trials generally. The jury has the benefit of the general instruction on credibility, of its own awareness of the witness’ criminality, and of the latitude given defense counsel to explore the witness’ possible interest, both by eliciting facts and by discourse in argument. If now the judge gives a special warning he may be unduly tilting the jury’s consideration.
In the case at bar, Ms. Wise’s testimony was materially corroborated, and hence it does not present the danger that an innocent person might be convicted solely on the prejurious fabrication of an alleged accomplice. Possession of controlled substances with intent to distribute was established not only by Ms. Wise’s testimony that such material was left with Lee but by the presence in Lee’s apartment of over $3000 in hidden cash and of drugs and material indicating a substantial wholesaling operation. Federal agents seized drugs of higher concentration than that normally used by addicts, suggestive of possession for sale. They also found glassine bags, measuring spoons, strainers, waxed paper bags, white paper bags, brown envelopes and dextrose — all used in the preparation of drugs for sale. This evidence may or may not by itself have been sufficient to convict.29 Indeed, much evidence, like the presence of the implements of drug preparation and adulteration, is consistent with the stories both of appellant and Ms. Wise. It is enough if there is evidence that confirms material points of an accomplice’s tale, and confirms the defendant’s identity and some relationship to the situation.30 *121The corroborative evidence need not resolve the conflicts between the accomplice’s testimony and an exculpatory version of the sequence of events.31
The Government’s corroborative evidence was an adequate basis to put the case to the jury, with the general instruction on witness credibility and without any special accomplice instruction directed against Ms. Wise, to decide, with full attention to the reasonable doubt standard and argument put by defense counsel, whether it accepted appellant’s version of events or that told by Ms. Wise.
3. Refusal of informant instruction
Appellant argues that the refusal to give a cautionary instruction concerning informant testimony is reversible error. He relies on United States v. Kinnard, 150 U.S.App.D.C. 386, 465 F.2d 566 (1972).
The trial court ruled that Ms. Wise was not an informant. Certainly not every person who is an informer within the meaning of the Government’s informer privilege — -which applies broadly to all citizens who communicate knowledge of crimes to police, yet wish to preserve anonymity32 — is within the purpose or scope of the cautionary instruction rule.
The cautionary instruction rule evolved as a special rule for paid informants. In Fletcher v. United States, 81 U.S.App.D.C. 306, 158 F.2d 321 (1946), Chief Judge Groner stressed the need for a special instruction where the only testimony connecting the defendant with unlawful sale of narcotics was that of a paid informant who was a drug addict. “Here, admittedly, the usefulness of the witness — and for which he received payment from the agent — depended wholly upon his ability to make out a case.” The court drew on the rule established in the jurisdiction that a jury be warned in the case of evidence given by a detective engaged in the “business of spying for hire.”
In Cratty v. United States, 82 U.S.App.D.C. 236, 242, 163 F.2d 844, 850 (1947), the court held Fletcher inapplicable in a case where there was material corroboration of the informer, applying the rule of Borum (supra, note 18) which removed the necessity for a special accomplice instruction where his testimony had corroboration.
The composite rulings had the effect of putting informers in the same status as accomplices in the sense that a cautionary instruction was required where there was no corroboration, or only minor corroboration that still left the government’s case hanging almost entirely on informant testimony,33 but dispensing with the need for a special instruction where there was material external corroboration of the informant’s testimony.34
In general, the various types of shabby witnesses — the accomplices, informers, false friends, lumped together in On Lee and Hoffa — are governed by similar rules, and the showing that no accomplice instruction is required, because of corroboration, obviates as well the need for an informant instruction.35
*122However, as to informant instructions, the problem was carried one step further in Kinnard, where this court evolved a special rule for what was emphasized as a narrow category of “narcotics addicts who are paid informers for the Government with criminal charges pending against them.” Such addict informers, it was pointed out, are subject to the special motive to lie, not only to make out cases as a matter of business,36 but also to be allowed to obtain urgently desired narcotics without the usual inhibitions of law. And often the addict-turned-informer seeks “not only to produce results for the police, but also to avoid retribution from powerful figures in the drug trade.” 37
In the very narrow class of addict-paid informants described in Kinnard, the existence of material corroboration would not obviate the cautionary instruction where there was a lack of corroboration on a central issue as to which informants as a class have a motive to lie, namely the issues of disposition and entrapment.
Kinnard plainly focused on what was the special danger arising out of the law enforcement practice of retaining paid informers prior to the commission of the offenses, generally to act as intermediaries between the police and those who will be identified by the informant. Such an informant presents particular dangers in regard to “producing” cases, e. g., including the development of claims that the transactions that evolved reflected predisposition on the part of the defendant as contrasted with entrapment.
The present case is lacking not only this “intermediary” aspect, but also any proof that Ms. Wise was paid for her information and testimony. While accomplices in general can be suspected, in the absence of corroboration, of testifying in the prospect of leniency, there is no similar general rule of experience that every witness for the Government is a paid informant. There was no evidence that Ms. Wise had been given any consideration in order to secure her cooperation and testimony.
Appellant argues that Ms. Wise has been allowed to plead to only one offense. But for this she got a five-year term. To mandate an informant’s instruction on this record would be tantamount to a rule requiring the trial judge to warn the jury to receive with suspicion the testimony of any Government witness who has recently pleaded guilty to an offense less than charged, or to only one out of multiple charges. There may be instances where such a suspicion is well-founded, but a judicial instruction of automatic suspicion cannot be justified. Plea bargaining is an everyday occurrence even when neither information nor testimony is sought, and is a practice sanctioned by the Supreme Court.38 In these so-called bargains the lesser plea may be only a fair scraping away of overcharging, or an awareness that additional prosecutions would likely result in concurrent sentences and be an unsound use of the resources of administration of justice. Compare United States v. Hooper, 139 U.S.App.D.C. 171, 432 F.2d 604 (1970).
It is urged that we remand for further inquiry into the circumstances surrounding Ms. Wise’s decision to testify. But there was no preclusion of such inquiry at the trial. Defense counsel took full advantage of his wide latitude to conduct a probing cross-examination of Ms. Wise in an effort to uncover before the jury facts that might bear upon her bias, including the facts of her guilty plea to a reduced offense, the length of her sentence, and indeed her implication in crimes, confessed on the stand *123(against the advice of her counsel), that were not made the subject of charge. Alford v. United States, supra; Davis v. Alaska, supra. On a record like this, there is no sound basis for an order of remand for more evidence.
4. Conclusion as to fair trial
It may be appropriate to conclude by tying together the threads of our discourse. This case concerns the infirmities of evidence, but the issues turn not on the law of evidence but on the law of trials. The dominant concern is for a fair trial by jury — fair opportunity to elicit evidence, and fair context for the jury’s consideration. Here counsel had full latitude to elicit evidence and argue in summation.
Turning to instructions, not every matter that may fairly be argued by counsel calls for an instruction. Thus, in a case where an accomplice is fully corroborated, counsel may argue to the jury concerning the dangers of accomplice testimony, although the judge will give no instruction, beyond that which gives guidance in assessing the credibility of any witness.
The instructions that a judge should give the jury on credibility call for a sound exercise of discretion. No universal formula can be stated, except perhaps that the judge should provide a fair and balanced perspective as context for deliberation. The baseline of doctrine sustains a judge who confines his credibilty instructions to generalized comment on the significance of a witness’s interest. Some cases may need more, but there is always the danger of oversteering and undue intrusion. Every time a judge is asked to caution the jury specially concerning a certain type of witness or witness’s interest, he must consider whether in the context of the trial he is not in effect singling out a witness or class in such a way as to give undue weight to one party or the other.
Certain exceptions have deleveloped as necessary for a fair trial. One requires that the jury be cautioned that the testimony of an accomplice is to be received with suspicion or caution and scrutinized with care. It is sustained by the general suspicion that the accomplice is testifying in hope of leniency, even though not established for the particular case. But the instruction is not required where the accomplice is materially corroborated, lest it oversteer the jury the other way. Another exception requires an instruction for the informant paid by the Government, lacking corroboration. But that imperative is not applicable in this case, where there was material corroboration and no evidence of consideration to the witness, either received, promised or expected. There was lacking the particular vice of an addict informant paid in advance of the offense, typically to serve as intermediary between the police and offender, where a caution is appropriate even though he is corroborated in substantial measure but there is no corroboration on the issue of entrapment or disposition.
We do not say that the trial judge would have erred in enlarging on the general instruction given in this case. Indeed, even in the days when no accomplice instruction was required by the Federal appellate courts,39 their opinions were studded with observations that such instructions were desirable.40 And so today in the instance where an accomplice or informant instruction is not required an appropriate instruction is often desirable.41 Accordingly, we note *124with approval the Government’s action in this case in suggesting to the trial judge that a cautionary instruction be given, an appropriate course as to instructions that are desirable though not mandatory.
Ultimately, the trial judge has the responsibility for shaping the charge. In giving a special cautionary instruction he must do so in the exercise of a sound discretion, and must give consideration to objections made on the ground of steering. One reason for insisting on a “request” as a condition for a requirement of instruction is to assure opportunity for consideration of the fairness of the instruction to both sides.
Perhaps defense counsel could have obtained a different general instruction from that given by the trial judge, say, with wording that all testimony be given “careful scrutiny.” 42 But what he sought was a special focus instruction, casting particular suspicion on the Government witness through delineation of a dangerous class of witnesses. Such special instructions are available, and even helpful, when used with discretion, but they are not mandatory when the shabby-source testimony has had significant corroboration.
With appropriate general instructions on interest of witnesses and full latitude to elicit evidence and argue in summation, we cannot say that the defendant was denied a fair trial.
* * * * * *
The arrival of the dissent leads to a few supplementary remarks.
1. It is suggested that this case calls for a remand on the question of whether Wise was an addict-informer.
The record reveals that the defendant had a full and fair opportunity to pursue this question at trial. The record contradicts any assertion that the trial judge limited Lee’s cross-examination of police officers on an issue that might possibly have assisted in establishing Wise’s status as an addict-informer.43
Obviously, the efforts of defense counsel to adduce evidence on the status of Ms. Wise could not possibly have been influenced by the trial judge’s denial of an informant instruction after the presentation of all the evidence.44
*1252. The principle of finality would be swept away by a practice of remanding whenever an appellate court’s review uncovers material lines of inquiry which counsel might have probed more effectively.
There is nothing in this record that remotely suggests a denial of a constitutional right to “effective assistance” of counsel. A lawyer is often well aware after a trial is over how he might have handled it more effectively, but that is no basis for scrapping reliance on counsel and the adversary approach.45
3. There is a special risk of unreliability in testimony of addict-informers, in that individuals who agree to secure evidence of crimes prior to their commission, in order to avoid criminal liability or sustain their addiction,- have a strong motive to manufacture crimes out of whole cloth. The dangers inherent in such “producing” eases are absent here. There is no indication that Ms. Wise agreed to serve as an intermediary between the police and Lee.
4. Even assuming Ms. Wise was an addict-informer under the standards established in Kinnard, the corroboration of her testimony obviated the requirement of an informer instruction.46 Corroboration need only provide independent evidentiary support for the witness’s account; it need not resolve conflicts between that account and the defendant’s version of the events. Otherwise, the more fantastic the defendant’s story, the harder it would be to secure this type of “corroboration.”
Affirmed.47