§ 354 [Offer of Proof Required to Challenge Exclusion]

If a judge wrongly refuses to let in certain evidence during a trial, you cannot automatically win an appeal because of that mistake. The verdict will only be overturned if the mistake actually caused a serious unfairness in the outcome, and there needs to be a clear record showing what happened.

To challenge the judge's decision on appeal, you generally need to show the court what the excluded evidence would have proven. This is usually done by explaining, on the record, what the evidence was and why it mattered. This is called an "offer of proof." Without this step, an appeals court often won't consider your argument, because there's no way to know if the evidence would have made a real difference.

There are some exceptions. If the judge's earlier rulings made it clear that trying to make an offer of proof would have been pointless, you don't have to go through that step. The same is true if the evidence came up during cross-examination or follow-up cross-examination, since attorneys often can't predict exactly what a witness will say in those moments. In short, this rule protects trials from being overturned over small evidence mistakes, unless someone can show the mistake really mattered and the issue was properly raised at the time.