One of the grounds for appealing a federal (or state) conviction is prosecutorial misconduct. It’s understandable to feel that a prosecutor was out to get you or was unnecessarily tough. However, that alone doesn’t rise to the level of prosecutorial misconduct. Like all attorneys, prosecutors must abide by legal and ethical rules and standards of conduct.
Some types of misconduct are fairly obvious. For example, withholding (suppressing) evidence that would be advantageous to the defendant or even exonerate them is obvious prosecutorial misconduct. So is fabricating or mischaracterizing evidence. One lesser-known but all-too-common type is referred to as “vouching.”
What does vouching look like?
Vouching can be done at any point in the trial, but it’s often done during the closing arguments. There are several common ways that prosecutors do it.
They may imply to the jury that there’s evidence that wasn’t presented during the trial (perhaps because it was suppressed) that indicates or proves a defendant’s guilt. That’s prohibited whether there is any such evidence or not.
Some vouching is more personal. A prosecutor may suggest or state that they personally believe the defendant is guilty – again, based on something other than the evidence presented to the jury. A prosecutor can’t just say, “Trust me. I’ve been doing this a long time, and I know that this person is guilty.” The case has to be made based on the (admissible) evidence and testimony.
While a prosecutor should personally believe that someone is guilty if they’re prosecuting them, that belief (or at least their public expression of that belief) needs to be based on evidence that was admissible at trial. Even if there’s evidence that wasn’t deemed admissible that indicates someone’s guilt, there was a reason for that. For example, if evidence was found during an illegal search, it’s a violation of the defendant’s rights for that to be used against them.
While defendants can’t be expected to recognize all behavior or words that constitute prosecutorial misconduct, defense attorneys and judges should recognize them. Nonetheless, prosecutorial misconduct can be a valid basis on which to appeal a verdict.