The issue presented calls for determination of the terms and legal effect of an oral stipulation made by counsel in open court. We are not here concerned with the interpretation of a document the terms of which are fixed by a writing. What the terms of the agreement were was properly a question *Page 50 of fact for the Trial Court. Romano v. Company, 95 N.H. 404. There was no express agreement, either by unilateral or mutual promises, to make a refund in advance of trial. In our opinion the Trial Court acted within reason in finding that plaintiff's counsel did not impliedly agree that his client should return the compensation payments. If the agreement was that the plaintiff "can't have both . . . she can't retain those payments and still pursue her common law remedy," this was no more than an agreement as to what the law was thought to require. The plaintiff was under no compulsion to agree to return the payments gratuitously; and experienced counsel are not given to obligating it client to the adverse party for the privilege of inspecting evidence commonly obtainable by legal process. At least the agreement could reasonably be found to relate to what the law required, and not to the performance of a voluntary undertaking for consideration. The view of the law upon which the parties agreed has proved to be mistaken. It is well settled that such agreements are not binding. "It is the general rule that stipulations as to what the law is are of no validity." 92 A.L.R. 663, 664. We would uphold the Superior Court in allowing the plaintiff her right to prosecute the common law action as permitted by Roberts v. Hillsborough Mills, 85 N.H. 517.