Role of “commercial context” in construing unambiguous contract

The parties in Ballard v. Devon Energy disputed when a provision in an oil field joint operating agreement, about the effect of “surrendering” certain leases, would apply.  No. 10-20497 (April 19, 2012)  The Court affirmed the denial of leave to amend the plaintiff’s contract claims to add a fiduciary duty count, based on a lengthy delay in raising the issue.  Op. at 6.  The Court then, applying Montana law, concluded that while the parties had both advanced “facially plausible” readings of the provision in isolation, the defendant’s reading was more persuasive in the overall context of the entire development project.  Id. at 12-15.  The Court affirmed summary judgment for the defendant, although it criticized the trial court for considering “extrinsic evidence” before attempting to construe the document on its face.  Id. at 9-10.