offer of proof
n. an explanation made by an attorney to a judge during trial to show why a question which has been objected to as immaterial or irrelevant will lead to evidence of value to proving the case of the lawyer's client. Often the judge will ask: "Where is this line of questions going?" and the offer of proof is the response. The offer provides the opposition a preview of the questions (and helps prevent surprise), but is essential to overcome the objections.