An offer of proof—also known as an informal bill of exception—is a procedure available during trial for the presentation of evidence the trial court has excluded. An offer of proof is made outside of the jury’s presence and often after the judge has sustained an objection to the admissibility of the evidence.

A bill of exception—also known as a formal bill of exception—is a procedure that allows a party to complain on appeal about evidence that would not otherwise appear in the trial record (because there was no offer of proof made at trial) by detailing the evidence (testimony, etc.) that would have been offered if the trial court had allowed it.

In Utah, an offer of proof is a procedural mechanism used during a trial to create a record of evidence that the court has deemed inadmissible. This is done outside the presence of the jury, typically after an objection to the evidence has been sustained by the judge. The purpose of an offer of proof is to preserve the excluded evidence for appellate review, by demonstrating what the evidence would have shown and why it is relevant and material to the case. A formal bill of exception, on the other hand, is a more antiquated procedure that is not commonly used in modern practice. It was traditionally used to document objections to evidence that was excluded without an offer of proof, to ensure that the appellate court could review the decision. However, most jurisdictions, including Utah, now have rules of procedure that have replaced the formal bill of exception with a more streamlined process for preserving a record for appeal. In Utah, the process for making an offer of proof is governed by the Utah Rules of Evidence and the Utah Rules of Civil Procedure, which outline the requirements for preserving issues for appeal, including the need to make a timely objection and an offer of proof when evidence is excluded.