Contractual Interpretation and Ad Hominem Rules of Construction

This chapter explores the problem of intractable uncertainty about the meaning of a contract. Legal systems have recognised this problem for millennia, though few have sought to pin down its precise nature or boundaries. One popular solution is the use of ad hominem rules of construction, which require us to choose the meaning that is more or less favourable to one of the parties: a classic example is the contra proferentem rule. Such rules have often been repurposed to address policy concerns, such as protecting consumers or vulnerable parties, and this has distracted attention from the core uncertainty problem. This chapter examines Western European discussions of the problem from Roman times to the present day, and canvasses the wide variety of rules that have been proposed to solve it. It demonstrates the flexibility of ad hominem rules of construction, and the diversity of the policy ideas that have been projected onto them.