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 Kentucky, an offer of proof is a procedural tool used during a trial when the court excludes evidence. This process allows the attorney to create a record of what the evidence would have shown, which is essential for appellate review. The offer of proof is typically made outside the presence of the jury, following a judge's ruling that sustains an objection to the evidence's admissibility. On the other hand, a bill of exception, also known as a formal bill of exception, is a mechanism that permits a party to preserve for appeal evidence that was not entered into the trial record and for which no offer of proof was made during the trial. This procedure involves documenting the excluded evidence in detail, such as testimony, to demonstrate what would have been presented had the court allowed it. Both procedures are critical for ensuring that a party's right to appeal is protected by providing a complete record of the proceedings, including any disputed evidence.