Yale law professor Ian Ayres continues his American Contract Law course with a short lecture on the scope of contractual obligation, using Alaska Northern Development, Inc. v. Alyeska Pipeline Service Co. as the case study. The discussion centers on UCC section 2-202, the parol evidence rule that governs when courts can look beyond a written contract to interpret its terms. Ayres walks through the dispute between the two companies to show how courts decide what evidence of prior agreements or negotiations may supplement or contradict a written contract's stated terms. The lecture is part of a Coursera-linked series, with the underlying case file made available separately for students to review alongside the video. It runs eleven minutes and assumes some familiarity with the course's earlier sessions on contract formation.