People negotiate agreements "in the shadow of the law," whether in the private ordering of affairs such as drafting contracts or in the public forum of settling lawsuits. A reverse phenomenon, however, has gone largely unnoticed: judges occasionally declare law in the shadow of negotiated settlements. In interpreting the terms of a consent decree when the parties themselves cannot agree on what obligations such terms impose, the judge may determine that both the words and the parties' own intentions are so ambiguous that the words must be interpreted in light of the substantive law that gave rise to the plaintiffs' claim. This writer has previously contended that the meaning of an ambiguous term should be determined, in part, "by reference to the constitutional or statutory rights sought to be vindicated in the litigation." Even if the law is somewhat uncertain, part of the judge's interpretive effort should be to determine which interpretation "will best serve the policies of the relevant law." It appears that the federal courts, at least, have adopted this position. This article explores the history of federal judicial interpretation of consent decrees and advocates a restrained approach to interpreting ambiguous settlement terms in light of the underlying substantive law. The proposed approach does not eliminate such a method of interpretation, but avoids the misguided effort of the D.C. Circuit in Microsoft I. Part I reviews the standards for interpretation of consent decrees that have emerged in the federal courts over the past three decades and sets forth a model of interpretation that is consistent with the emergent caselaw. Part II examines the problem of interpretation that arose in Microsoft I and analyzes the difficulties posed by the D.C. Circuit's declaration of substantive antitrust law in that case. Part III discusses the policy considerations that should be weighed in determining the extent to which judges should declare law "in the shadow of" negotiation. The Conclusion argues that it is appropriate for courts to interpret ambiguous terms in consent decrees in light of underlying substantive law if other extrinsic evidence of the parties' intent surrounding the negotiation of the terms does not clearly resolve the issue. If the issue of law is not properly before the court, however, or if the law is not reasonably clear, courts should not decide what the law is, but instead should interpret ambiguous terms based solely on other extrinsic evidence of the parties' intent. Furthermore, if the law is clear, the court should follow it rather than decide what it thinks the law should be.