When a judge excludes proposed testimony or evidence, the party offering it can make an offer of proof — a description, on the record, of what the excluded evidence would have shown — to preserve the issue for appeal. Without an offer of proof, an appellate court often has no way to assess whether the exclusion was harmful, since it cannot know what the excluded evidence actually would have said.

An offer of proof can be made through a summary by counsel, through the witness's actual testimony outside the jury's presence, or through a written proffer, depending on the court's practice and the nature of the evidence. Courts generally require the offer to be specific enough to let both the trial judge reconsider the ruling and an appellate court later evaluate whether the exclusion was erroneous and whether it affected the outcome.

In Juricratic's evidence record, an excluded or contested piece of evidence keeps its full content and provenance even when a simulated matter models it as inadmissible, mirroring the function an offer of proof serves in a real courtroom — the material is not discarded just because it did not make it into the admitted evidence set.

Trial counsel makes a clear, specific offer of proof immediately after an adverse evidentiary ruling, rather than assuming the point is obviously preserved, because a vague or missing offer of proof is a common and entirely avoidable reason an appellate court declines to review an exclusion ruling at all.