Deon Love was convicted of a federal firearm violation and was sentenced to 120 months’ incarceration. He argues that his Sixth Amendment right of confrontation was violated when the district court imper-missibly restricted his cross-examination of three government witnesses — -William Craig Thomas, Tommy Cummings, and Chris Davis. More specifically, Love urges that the district court’s limit on his examination of Thomas is of “particular significance.” We agree. 2 The district court’s constraints on Love’s cross-examination of Thomas — a crucial adverse witness — violated the Confrontation Clause of the United States Constitution. Accordingly, we reverse Love’s conviction and remand for new trial.
I.
Background
On January 23, 2002, a two-count indictment was returned charging Love with being a felon and drug user in possession of a firearm and selling a stolen firearm. 3 After trial, on May 21, 2002, a jury acquitted Love on the selling charge, but concluded that he was guilty of illegally possessing a firearm.
In support of the government’s claim that Love — an undisputed felon — illegally “possessed” a firearm, the jury heard from only one witness who actually observed Love with a firearm. Thomas testified that on April 27, 2001, he saw Love with a “rifle” or “shotgun” and a “little revolver.” Thomas stated that Love offered to sell him these weapons because Love was a felon and could not legally possess them. According to Thomas, he declined Love’s offer, and Love maintainеd possession of the firearms.
In response to this testimony, Love attempted to cross-examine Thomas about his mental disability. The district court sustained the government’s objection to any inquiry into Thomas’s mental disability. 4 Love proffered evidence 5 to the court that Thomas had been diagnosed with *984 schizophrenia and a short- and long-term memory impairment. Love argued that Thomas’s mental illness — specifically his impaired memory — was relevant to his ability to competently recall and recount events more than a year after they allegedly occurred.
On appeal Love acknowledges that Thomas’s schizophrenia diagnosis is of questionable relevance and instead concentrates his argument on Thomas’s disabled memory. Similarly, our analysis is limited to whether the district court too narrowly limited Love’s cross-examination of Thomas’s impaired memory.
II.
Discussion
The Sixth Amendment guarantees a defendant an opportunity for effective cross-examination of witnesses.
United States v. Warfield,
Accordingly, we begin with a consideration of Love’s right to challenge the accuracy of Thomas’s testimony with evidence that Thomas might have a mental defect. As the Fifth Cirсuit has noted, “a defendant has ‘the right to attempt to challenge [a witness’s] credibility with competent or relevant evidence of any mental defect or treatment at a time probatively related to the time periоd about which he was attempting to testify.’ ”
United States v. Jimenez,
The government urges us to affirm because “the district court had ample oppor *985 tunity to observe Thomas’s demeanor[,] to conclude that Thomas was not then suffering from the defect[,] and was able to competently recall events from the past.” However, the government’s argument misunderstands the role of the district court— it is to determine the relevance of a witness’s reported mental defect. We do not expect the distriсt court to assume the role of a mental-health expert, and we recognize that the existence of a mental condition, which bears on competence, may not be discernible from a witness’s demeanor.
In this case, upon Love’s inquiry into Thomas’s disability, 6 Thomаs answered “diabetes” and then promptly objected to any further questioning. The district court sustained the objection without hearing any evidence of the witness’s malady. Evidence of Thomas’s impaired memory diagnosis was first introduced during Lоve’s proffer. After becoming aware of the witness’s alleged long- and short-term memory affliction, the district court again sustained the objection and offered no comment on the matter.
We are convinced that the district сourt violated Love’s right of confrontation when it sustained Thomas’s objection. First, we examine the nature of the psychological problems.
Collins,
Despite finding error below, our inquiry is not complete. We must now consider whether the record shows “beyond a doubt that the error сomplained of did not contribute to the verdict obtained.”
Van Arsdall,
Considering these factors, it is impossible for us to conclude that the еrror in limiting the cross-examination of Thomas was “harmless beyond a reasonable doubt.”
Van Arsdall,
The government argues that “even if the testimony of Thomas was disregarded in its entirety, [the] ... case against Love was strong.” We are not so convinced. The other witnesses — offered to support the selling charge of which Love was acquitted — testified that at no time during the alleged sale did they observe a firearm in Love’s possession. Thus, if the testimony of Thomas was disregarded, then the government is left with less than overwhelming evidence of Love’s guilt, and we are unable to say that the court’s error was “harmless beyond a reasonable doubt.”
Caldwell,
III.
Conclusion
In conclusion, only one witness — Thomas — stated that he actually observed Love possess a firearm. Love was barred from pursuing a fine of questioning into this critical witness’s impaired memory diagnosis. This limitation denied Love his constitutionally-guarantеed right to effectively cross-examine Thomas, and we cannot definitively state “that this denial did not contribute to the verdict obtained.”
Id.
at 678-79,
Notes
. Appellant argues — as support for his primary argument of error — that the district court made three other minor cross-examination errors. However, we disagree with appellant's assertion, and find no error in the three other cross-examination issues raised on appeal. Accordingly, our review is isolated to appellant's primary allegation of error.
. See 18 U.S.C. §§ 922, 924 (1994).
. Interestingly, it was actually Thomas who made the objection — not the government — as to inquiry into his mental defect. Neither the government nor Thomas offered a basis for the objection. The district court sustained the objection without comment.
. The precise proffer is as follows:
What I wanted to question him on is statements or an opinion that Dr. Novelus who *984 submitted a report in favor of his mental disability, and Mr. Thomas did receive that disability, Your Honor, Dr. Novelus determined that Mr. Craig Thomas has — his short-term memory and long-term memory are impaired. He has severe mental impairments and he could also be an intrinsic schizophreni[c], which I can see where that possibly may or may not be as relevant, but, Your Honor, I certainly wanted to be able to question him regarding his mental ability and his impairments. I think it went — it goes directly to his ability to be a competent witness relating facts over a year old.
Appellant’s Br., at 16.
. In a footnote the government argues thаt once Thomas responded that his disability was "diabetes,” Love was barred from offering extrinsic evidence to impeach the answer. The government cites
United States v. Elliott,
. The genesis of Thomas's disability diagnosis is a psychological examination that he voluntarily submitted to in order to potentially— and in his case, successfully — be entitled to early release from incarceration.
