The Tenth Circuit Court of Appeals in United States v. Commanche reversed a conviction for assault with serious bodily injury based upon the improper admission of two aggravated battery convictions.

Bryan Commanche got into a fight after a friend punched him, accusing him of getting too close to the friend’s girl friend. He pulled out a box cutter and wounded the aggressor who was considerably bigger than Commanche. At trial he claimed that he acted in self defense but the jury found him to be guilty after the prosecution introduced evidence that Commanche had two convictions for aggravated battery.

The trial court allowed not only the fact of the convictions but also details about the convictions including the fact that both of the prior bad acts were committed with sharp instruments.

The trial court denied Commanche’s motion in limine to exclude the priors on the basis of Federal Rules of Evidence 404(b) and 609(a)(1).

The appellate court found that the prior convictions were not admissible under Rule 404(b) which prohibits the admission of prior convictions where the only purpose of the admission is to show bad character. The trial court admitted the evidence purportedly to show Commanche’s intent. But the appellate court found that the only way a jury could believe that the prior convictions reflected Commanche’s intent is if the jury first found that the convictions proved that he was violent. This is exactly the type of character evidence prohibited by Section 404(b). Thus the court found that it was error to admit the prior bad acts under Section 404(b).

However, since Commanche testified at trial the convictions could be used for impeachment under Section 609(a)(1) The rule says:

For the purpose of attacking the character for truthfulness of a witness, (1) . . . evidence that an accused has been convicted of . . . a [felony] shall be admitted if the court determines that the probative value of admitting this evidence outweighs its prejudicial effect to the accused . . . .

But while the fact of the convictions can be put before the jury the court found that under well established law the details of the prior conviction are inadmissible. Furthermore, the admission of the details of the prior convictions, specifically the fact that they were committed with sharp instruments was enough to sway the jury considering the facts of the case, the errors were not harmless and reversed the conviction.