How have the courts interpreted plea agreements between a defendant and federal authorities?

courts have necessarily drawn on the most relevant body of developed rules and principles of private law, those pertaining to the formation and interpretation of commercial contracts. But the courts have recognized that those rules have to be applied to plea agreements with two things in mind which may require their tempering in particular cases. First, the defendant's underlying "contract" right is constitution-ally based and therefore reflects concerns that differ fundamentally from and run wider than those of commercial contract law. Second, with respect to federal prosecutions, the courts' concerns run even wider than protection of the defendant's individual constitutional rights--to concerns for the honor of the government, public confidence in the fair administration of justice, and the effective administration of justice in a federal scheme of government.

United States v. Harvey, 791 F.2d 294, 300 (4th Cir.1986) (citations and internal quotation marks omitted).