Whether Espinal's prior cocaine use and use of Xanax rendered her incompetent to testify or required exclusion of her testimony.
Holding
No. Espinal was competent under Federal Rule of Evidence 601, and the district court did not abuse its discretion by allowing her to testify.
Reasoning
The court distinguished witness competency from witness credibility. Credibility ordinarily concerns whether the jury should believe a witness, while competency is a threshold question for the judge. Rule 601 establishes a broad presumption that every person is competent to testify, and the Federal Rules specifically disqualify only limited classes, such as judges and jurors in the circumstances covered by Rules 605 and 606.
A witness's impairment may sometimes justify exclusion through other evidentiary rules. For example, Rule 603 may exclude a person unable to take or understand an oath, Rule 602 requires personal knowledge, and Rule 403 permits exclusion when unfair prejudice substantially outweighs probative value. But those determinations are discretionary and are reversed only for a clear abuse of discretion.
Nothing in the record showed that Espinal was impaired so severely that she could not give meaningful testimony. She had been free of cocaine for five months before trial, was not under cocaine's influence when she testified, had testified credibly in two previous related trials, and gave lucid testimony in Ramirez's trial.
The defense psychiatrist's proposed testimony about Xanax was general and speculative. The psychiatrist suggested only that Xanax could make some people sufficiently placid that cross-examination might be less effective. That possibility did not establish that Espinal lacked competence, especially because cross-examination tests factual inconsistencies rather than merely a witness's emotional composure.