Consent decrees -- the unheralded workhorses of regulatory law -- play a critical role in environmental law. The bulk of major environmental disputes at the federal level are resolved through consent decrees lodged under judicial supervision, and key federal environmental statutes and policies directly require settling parties to use consent decrees to resolve their claims. These proposed decrees, however, typically receive only a restrained judicial review that does not yield a formal judicial opinion on the full merits of the agreement. Parties, in fact, will frequently insist that the decree will not involve an admission of liability or any conclusions of law. As a result, consent decrees operate as the dark matter of environmental law -- an unseen supporting medium that surrounds and supports the statutory and regulatory directives that function within it, but which leaves few marks of its own. These decrees play a similar role in several other legal fields, including antitrust, consumer protection, class actions, labor, and bankruptcy. Most of the public and scholarly scrutiny of consent decrees has focused on concerns about their potential effects on third parties and their constraints on future executive discretion or administrative action without proper democratic accountability or transparency. This Article reverses that perspective. It assumes that consent decrees can appropriately create and foster emerging legal principles, and it suggests strategies to identify these new legal holdings. This Article proposes three ways by which consent decrees substantially influence the development of environmental law and flag new emerging principles. First, consent decrees can serve as a platform to implement nascent regulatory policy prior to the formal promulgation of rules or regulations. In a sense, consent decrees in these circumstances provide a test bed for new environmental practices and expectations that later mature into full-fledged regulatory standards. This function of consent decrees tends to surface most visibly during coordinated enforcement initiatives involving industrial sectors at the federal level. Second, consent decrees can generate new law through deferential review by the courts that lodge them. When courts weigh a proposed consent decree to determine whether to accept it, they use a relaxed review standard that does not require the court to closely assess the merits or legal conclusions of the settlement. Such a review parallels, in many respects, the deferential judicial review of administrative agency action under the federal Administrative Procedure Act. This historical deferential review of agency action nonetheless has sketched the contours of numerous important principles of environmental law; relaxed judicial determinations of the legality and fairness of consent decrees may play a similar role. Last, and most controversial, consent decree judgments arguably can directly embody legal holdings that, at minimum, have persuasive value for subsequent court proceedings. These holdings, in certain circumstances, might even rise to the level of precedential rulings entitled to stare decisis in future actions. This final role of consent decrees in generating environmental law, however, requires careful consideration to avoid the risks of manipulation or erosion of judicial authority. [ABSTRACT FROM AUTHOR]