So, you have a prosecution witness who testifies to something on the witness stand which you know is wrong and for which you have contradictory evidence. Let’s also assume for the moment that the wrong testimony is about something relevant to the case and you are not in a situation where you can impeach through prior inconsistent statements. Federalevidence blog has a case discussing impeachment through contradiction.
Drawing the line between evidence that probes the character and conduct of a witness through use of "specific incidents" of misconduct under FRE 608(b) and evidence aimed at directly contradicting the witness’s contentions, can be difficult to draw. A recent case of the Third Circuit explored this difference between evidence excludable under FRE 608(b) and evidence admitted as evidence of "impeachment by contradiction." Admission of the impeachment by contradiction evidence is subject to limits, not from FRE 608(b) constraints, but rather by FRE 403‘s balance of the probative value against the possible prejudicial impacts of the evidence.
Impeachment by contradiction allows “courts to admit extrinsic evidence that specific testimony is false, because contradicted by other evidence,” citing to United States v. Castillo, 181 F.3d 1129, 1132–33 (9th Cir. 1999). Impeachment by contradiction is “a means of policing the defendant’s obligation to speak the truth in response to proper questions,” citing to United States v. Gilmore, 553 F.3d 266, 271 (3d Cir.2009).
So, you’ll understand my assumptions if trying to use this rule of evidence:
a. The contradicted testimony must be relevant, and I think it’s fair to say, important to the credibility question and the case.
b. The contradictory evidence should be specific.
c. The military judge has to balance admission under Mil. R. Evid. 403.