Prosecution of D for grand larceny. The prosecution calls W1, who testifies that D admitted to committing the crime. In response, D intends to call W2, W1s former girlfriend, to testify that that W1 has a medical history of delusions and amnesia that affected his ability to perceive and recall reality. The prosecution objects claiming improper impeachment.
How should the court rule?
Objection overruled (most likely). W2s testimony is sought to impeach W1s capacity to perceive and accurately recollect the confession. Assuming D clears all privilege, relevancy, and witness-competency hurdles, the court would weigh the probative value of the impeachment against its danger of unfair prejudice, confusion of the issues, misleading of the jury, undue delay, and cumulativeness of the evidence. FRE 403. It would be better to call W1s physician since W2s lay opinion is not as competent. But that would raise questions about the weight of the testimonynot its admissibility.