dissenting:
I believe that the trial court erred in excluding the defense’s proffered cross-examination of the government’s key witness to establish her bias and motive for testifying as she did.1 Therefore, I would reverse and remand for a new trial.2
1. Preclusion of cross-examination on neglect proceedings
The trial court did not permit counsel to question the complaining witness as to whether she was afraid that she might “get in trouble with the police”3 on the ground that the witness denied having done anything wrong. Later in the cross-examination, defense counsel proffered that he had information that two of the complaining witness’s children had been removed from her custody and that she had been warned that two other children still living with her also might be removed from her care and placed in a foster home. Counsel added that even though he had not seen the file jacket in that case, which was confidential, he believed it was an “abuse and neglect type situation” that had resulted in the children being removed from the home. He argued that in light of the adjudication of neglect of two of her children and the warning about a possible additional neglect proceeding for her other children, the complaining witness had reason to lie or shade the truth about what had occurred in her encounter with appellant because if she admitted to having used drugs or participated in violent behavior, she could jeopardize her ability to regain or maintain custody of her children. The *36trial judge did not permit the cross-examination, ruling that the proffer was “too speculative” and. that, “even if the facts happened here [in the criminal case] that she was the aggressor, it would not be a basis for a neglect or an abuse .... There has to be a factual basis before I would allow you to pursue that. You have not made one ... I think you have to have even more to entitle you to that .... ” The trial judge also considered that the line of questioning was prejudicial, because the inquiry would “embarrass” the witness and would “further dirty her and make her less sympathetic.”
The Confrontation Clause of the Sixth Amendment to the U.S. Constitution guarantees a criminal defendant the opportunity for effective cross-examination of adverse witnesses. See Delaware v. Van Arsdall, 475 U.S. 673, 678, 106 S.Ct. 1431, 89 L.Ed.2d 674 (1986); Davis v. Alaska, 415 U.S. 308, 315-16, 94 S.Ct. 1105, 39 L.Ed.2d 347 (1974); Alford v. United States, 282 U.S. 687, 691-92, 51 S.Ct. 218, 75 L.Ed. 624 (1931). A trial court violates a defendant’s right to confrontation when the court prohibits the defendant from “engaging in otherwise appropriate cross-examination designed to show a prototypical form of bias on the part of the witness” thereby exposing facts “from which jurors ... could appropriately draw inferences relating to the reliability of the witness.” Van Arsdall, 475 U.S. at 680, 106 S.Ct. 1431 (quoting Davis, 415 U.S. at 318, 94 S.Ct. 1105). We have held that “bias or testimonial motivation is always a proper subject of cross-examination,” Clay borne v. United States, 751 A.2d 956, 962 (D.C.2000), and that the bias of a witness is “never” a collateral issue, In re C.B.N., 499 A.2d 1215, 1218 (D.C.1985).
In considering the admission of proposed cross-examination for bias, the trial court performs its usual role of weighing the proffered evidence’s probative value against its prejudicial effect on the fair and efficient conduct of the trial, and need not permit cross-examination on topics of marginal relevance simply upon the possibility that bias or prejudice might be disclosed. See Greene v. McElroy, 360 U.S. 474, 496, 79 S.Ct. 1400, 3 L.Ed.2d 1377 (1959). But a defendant is entitled to pursue all avenues of cross-examination reasonably calculated to expose a motive, bias, or interest for the witness to testify. See Van Arsdall, 475 U.S. at 680, 106 S.Ct. 1431. “While the scope of cross-examination is within the discretion of the trial judge, this discretionary authority to limit cross-examination comes into play only after there has been permitted as a matter of right sufficient cross-examination to satisfy the Sixth Amendment.” United States v. Elliott, 571 F.2d 880, 908 (5th Cir.1978) (citation omitted). Thus, error is shown when a reasonable jury might have had a significantly different impression of the witness’s credibility if the defendant’s counsel had been permitted to pursue an appropriate line of questioning. See Clayborne, 751 A.2d at 962. Once a good faith proffer of bias is presented to the trial court, the jury should learn of a witness’s bias, unless the probative value of the evidence is “substantially outweighed” by the risk of undue prejudice. Id. at 962-63.
In this case, the trial court applied an incorrect legal standard in excluding cross-examination about the witness’s fears stemming from the ongoing neglect case involving her children. By focusing on whether the complaining witness’s aggressive conduct toward appellant would be “a basis” to establish neglect toward her children, the trial court missed that what is relevant in evaluating bias is not what the law or a judge considers sufficient to prove neglect, but the witness’s subjective belief. “[I]t is this belief that can produce bias.” Scull v. United States, *37564 A.2d 1161, 1165 (D.C.1989). Because the trial court applied an incorrect legal standard in determining relevance, it did not grasp the probative value of the proffer. Having misunderstood the relevance of the proposed line of questioning, the trial court precluded the inquiry based solely on its perceived prejudice to the witness. Therefore, its balancing of probative value and prejudice was inherently flawed.
Because cross-examination was precluded, the witness’s understanding of what admissions would expose her to criminal liability was not explored. Lay persons frequently have mistaken notions about the law, and this could be particularly so in cases of domestic violence, where lay persons are uncertain about the reach of the criminal law into what many consider to be their private affairs. Nor do we know what the witness thought her criminal exposure might be if she were to admit to being something more than the passive victim of an assault. The outcome in this case, for example, shows that appellant was acquitted of the felony charges and convicted only of simple assault, for which he was sentenced to 180 days incarceration. Of particular importance in this case would be the witness’s understanding of the risk of conviction in a criminal proceeding where the government has the burden of proving guilt beyond a reasonable doubt against the prospect of continued intervention by child welfare agencies — particularly once neglect has already been found — where the standard is focused on the “best interest of the child.” D.C.Code § 16-2320(a) (2001). There is much less tolerance for parental misbehavior in the child neglect system than in a criminal proceeding.
The witness’s motivation to he to avoid inculpating herself in this case was, as Judge Schwelb says, “surely obvious to any reasonably intelligent juror.” See ante at 32. We cannot presume that if the witness would lie, however, she would do so only and to the same extent to avoid implicating herself in the criminal offense, and not because of concerns related to the child neglect proceeding.4 Whereas that might be a valid assessment in certain cases, that is not necessarily how the witness in this case would think, and it was the jury’s prerogative — not ours — to hear and evaluate her testimony on these matters. Though trial judges must perforce attempt to evaluate the relevance of evidence in making admissibility determinations, where the issue is cross-examination for bias, judges should be particularly sensitive not to usurp the role of the jury. As opposed to evidentiary calls where the judge performs a gatekeeping function in order to exclude irrelevant evidence or evidence presumed to be prejudicial, where the Confrontation Clause is implicated the gate is purposely left ajar. The importance of the interest protected by the Confrontation Clause tips the scales in favor of permitting cross-examination such that “[t]he broad discretion afforded the trial court as to the extent of cross-examination ‘cannot ... justify a curtailment which keeps from the jury relevant and important facts bearing on the trustworthiness of crucial testimony.” ’ Bennett v. United States, 797 A.2d 1251, 1257 (D.C. *382002) (quoting McCloud v. United States, 781 A.2d 744, 752 (D.C.2001)).
Bias is present in every case where the witness’s own potentially criminal conduct is implicated in the charged offense. Precisely because it is so commonplace, that kind of bias is likely to be expected by the jury. It is more likely to be discounted in the jury’s assessment of the witness’s credibility, however, where the witness is testifying on behalf of the government — as in this case — and in the eyes of the jury benefits from an aura of credibility created by the government’s decision to charge the other person involved in the fray. Thus, there is added importance to presenting concrete information so that the jury can evaluate the precise pressures at work on the witness. The bias that defense counsel was attempting to reveal in this case through cross-examination about the neglect proceeding was specific and more, unusual. It could have had real impact because it involved something not obvious to the jury, that was not part and parcel of what the jurors would normally have expected in a he said-she said situation such as this. In this case there was reason to believe that the witness’s understanding about the workings of the neglect system and her fear of how her testimony in this criminal case might affect decisions concerning her children in the neglect case, would give her a strong motive to lie or, at least, minimize her culpability in order to “look good” in the eyes of those judging her in the context of the neglect case. This motivation is akin to the well-reeog-nized bias of a witness in favor of the prosecution in the hope of obtaining better treatment for her own crimes in a different case either while on probation, see Davis, 415 U.S. at 818, 94 S.Ct. 1105 (evidence of prior juvenile offense admissible to afford a basis for an inference of undue pressure because of the witness’s vulnerable status as a probationer), or while on parole, see State v. Luzzi, 147 Conn. 40, 156 A.2d 505, 507 (1959) (right to establish motive of witness to “color her testimony” so as to “absolve herself from as much blame as possible and thereby gain[] for herself more lenient treatment”). A jury could well understand that a mother whose children have been adjudged neglected while in her care feels she is “on probation” during the time that the child welfare authorities are monitoring her behavior in considering whether to return children to her home or remove those who are still there.
The witness’s fear — whether reasonable or not — that her actions in the melée with appellant might influence decisions concerning her children would have given the jury important insight into a specific force motivating her testimony — and the strength of that motivation. The fear of losing custody of children and the stigma associated with it cannot be assumed to be of less importance than the fear of conviction and even incarceration, as each deals with different social values. See Commonwealth v. Piedra, 478 N.E.2d 1284, 20 Mass.App.Ct. 155, 157 (Ma.1985) (reversible error to bar “specific inquiry on the issue of motive” even though inquiry allowed into witness’s bias in general). The trial judge was concerned that evidence of the neglect adjudication could “embarrass” and “further dirty” the witness before the jury. That concern is but a recognition of the importance that our society places on child neglect, and the witness — as well as the jury — is influenced by those values. The jury could believe that the witness would have been powerfully influenced by maternal concern for her children as well as by the stigma that the judge recognized attaches to a determination of neglect. For some, this could be a fate worse than incarceration. Cf INS v. St. Cyr, 533 U.S. 289, .322, 121 S.Ct. 2271, 150 L.Ed.2d 347 *39(2001) (citing Magana-Pizano v. INS, 200 F.3d 603, 612 (9th Cir.1999) (“That an alien charged with a crime ... would factor the immigration consequences of conviction in deciding whether to plead or proceed to trial is well documented.”); 3 BENDER’S CRIMINAL DEFENSE TECHNIQUES §§ 60A.01, 60A.2[2] (1999) (“Preserving the chent’s right to remain in the United States may be more important to the client than any potential jail sentence.”)).
Any concern the trial judge reasonably had about jury confusion or taint from evidence that Johnson had been adjudged a neglectful mother could have been addressed by a limiting instruction on the proper use of the evidence. All that the jury needed to know was that there was a pending neglect proceeding and, without going into unnecessary detail, that Johnson feared the impact that her testimony in the criminal case could have on that proceeding. Complete exclusion “bears a very heavy burden of justification when lesser restrictions are available.” Brown v. United States, 740 A.2d 533, 537 (D.C.1999). Thus, I conclude that it was error to exclude the cross-examination into Johnson’s concern about the child neglect proceedings.
2. Harm
Restrictions on cross-examination require reversal depending “upon the scope of cross-examination permitted by the trial court measured against our assessment of the appropriate degree of cross-examination necessitated by the subject matter thereof as well as other circumstances that prevailed at trial.” Flores v. United States, 698 A.2d 474, 479 (D.C.1997) (citation omitted). The Confrontation Clause is violated and we apply the constitutional harmless error test of Chapman v. California, 386 U.S. 18, 22-23, 87 S.Ct. 824, 17 L.Ed.2d 705 (1967), whenever “the trial court precludes ‘a meaningful degree of cross-examination’ to establish bias.” Grayton v. United States, 745 A.2d 274, 279 (D.C.2000) (quoting Flores, 698 A.2d at 479); see also Scull, 564 A.2d at 1166. Here, the trial court’s ruling prohibited defense counsel from exposing Johnson’s bias and motive to he arising from the neglect case, an entirely separate line of relevant questioning, depriving appellant of a “meaningful degree of cross-examination.” See Grayton, 745 A.2d at 279. Applying the Chapman standard to violations of the Confrontation Clause, we must be able to say, beyond a reasonable doubt, that even if the jury had been convinced that Johnson was motivated to he because of concern about the neglect proceeding, it would have convicted appehant of assault. See Scull, 564 A.2d at 1166. In this case that is tantamount to saying that appehant would have been convicted “without [Johnson’s testimony].” Id.
On this record, I must have a reasonable doubt because Johnson’s testimony was the key to the government’s case. She and appehant testified to completely different versions of events, and there was no other eyewitness testimony. Although Johnson sustained more serious injuries, appehant also was burned on his arm— injuries that could be explained by either one’s version of the incident. Moreover, there was circumstantial evidence to support appehant’s story: Johnson had behaved aggressively toward appehant on previous occasions; out of jealousy she had threatened other women in the past; her version of events was inconsistent and implausible; and she previously had denied that appehant assaulted her in this instance. Renae Dreher, an impartial witness, testified that Johnson had a reputation for violence and dishonesty. The admission of the proffered bias evidence was thus critical to the defense case, which hinged on showing that Johnson, who was shown to have been untruthful in the past, *40in this case had a strong motivation to he again in order to protect her relationship with her children. Though Johnson’s reports to the police and doctor made soon after the incident could have been viewed as more reliable than her in-court testimony, the verdict makes clear that the jurors did not credit those statements any more than her trial testimony, or they would have returned a guilty verdict on at least one of the felony charges. There is no substantial difference between Johnson’s testimony in court and what the police and doctor reported she said to them right after the incident.5 Because the government’s case was grounded on Johnson’s credibility and the jury’s verdict clearly discounted most of the government’s case, I cannot conclude beyond a reasonable doubt that the erroneous preclusion of cross-examination that would have given the jury a complete picture of the extent of Johnson’s bias would not have made a difference. Had the jury heard about the pending neglect case and Johnson’s feelings about it, the jury could have inferred that Johnson understandably felt she was under close scrutiny and, as a result, would deny any involvement with drugs and aggressive action out of fear that negative conduct on her part — even if insufficient in her eyes to constitute criminal behavior — would weigh against her in the neglect proceedings. A jury that believed Johnson was on drugs and aggressive on that occasion could well have believed appellant that it was not he who assaulted Johnson but vice-versa.
I would reverse and remand for a new trial.
. I join Judge Schwelb’s opinion with respect to the other issues raised on appeal.
. Judge Farrell agrees that the limitation on cross-examination was constitutional error, but affirms the conviction because he considers the error to have been harmless.
.Defense counsel asked the witness:
... My question I want you to answer is you know you could get in trouble if the police found out you did something wrong on May 29?
. According to Judge Schwelb, “[tjhere is no reasonable possibility that Ms. Johnson would tell the truth even if it meant going to prison (and probably losing custody of her children), but would lie in order to avoid impairing her chances of retaining or regaining custody.” See ante at 32. Under the relevant statute, however, incarceration does not automatically lead to loss of custody. See D.C.Code § 16-2301(9)(c) (a neglected child is one “whose parent ... is unable to discharge ... her responsibilities to and for the child because of incarceration, hospitalization, or other physical or mental incapacity”).
. The essence of Johnson s in-court testimony and her reports to the police and doctor at the time was the same: that appellant had become angry and thrown a hot liquid at her, scalding her face, neck and arms.