C ongress has created numerous federal agencies charged with carrying out a broad array of delegated statutory responsibilities. Agencies administer their delegated authority in a variety of ways, including by promulgating rules and regulations that bind the public, advising regulated parties of an agency's enforcement priorities via guidance documents, bringing enforcement actions against private individuals or corporations for violation of a statute or regulation, and determining whether to grant a benefit or license. These agency actions, in turn, often generate questions about the legitimacy of an agency's decision. Individuals affected by an agency decision can sometimes challenge that action in federal court as violating a legal requirement. The U.S. Constitution vests the judicial power in the Supreme Court and any inferior courts established by Congress, limiting the power of federal courts to the context of a of a "case" or "controversy." Pursuant to this authority, Congress has established federal courts below the Supreme Court of the United States to hear a variety of cases, both criminal and civil. Federal legislation authorizes courts to adjudicate challenges to actions taken by government officials and agencies in a variety of contexts. Federal courts are, however, courts of limited jurisdiction—they must adhere to limits placed on their authority by Congress and the Constitution. The circumstances under which a federal court will review the actions of a U.S. government agency or official thus involve complicated questions of statutory and constitutional law. This report offers a brief overview of some of the most important issues arising when individuals bring suit in federal court to challenge agency actions. The Administrative Procedure Act (APA) is perhaps the most prominent modern vehicle for challenging the actions of a federal agency. Enacted in 1946 following the New Deal era, during which the size of the administrative state was expanded, the statute represents the first government-wide attempt to "systematize" requirements on the actions of federal agencies. The APA functions as the most prominent authorization of judicial review of agency action, including for agency compliance with substantive legal requirements—such as an agency's "organic," or authorizing, statute. In addition, the APA imposes various procedural requirements on federal agencies and authorizes courts to review agency's compliance with these requirements. Accordingly, the focus of this report is largely centered on judicial review of agency actions under the APA. The report opens with a discussion of the circumstances in which federal courts are empowered to review agency actions and follows with a look at the scope of review authorized by the APA. It then continues by describing the mechanics of a federal court's review of an agency's statutory authority, as well as the standards employed in the review of an agency's discretionary decisions. The report concludes with a brief examination of judicial review of agency compliance with statutorily prescribed procedural requirements. Not every agency action is necessarily subject to judicial review. Whether judicial review of agency action is available in federal court turns on a number of factors, including constitutional, prudential, and statutory considerations. Courts must possess statutory jurisdiction to adjudicate a lawsuit, and plaintiffs must generally rely on a cause of action that allows a court to grant legal relief. Disputes must also present "cases" or "controversies" that satisfy the requirements of Article III of the Constitution. Finally, a suit must be presented to a court at the proper time for judicial review. The federal courts are courts of limited jurisdiction. Their authority is restricted to matters entrusted to them by Congress. Consequently, in order to adjudicate a case, a statute must bestow subject matter jurisdiction in a federal court over a particular claim. In addition, suits against the United States are barred absent a statutory waiver of sovereign immunity. As a threshold matter, courts must possess subject matter jurisdiction over a claim to hear a case. Subject matter jurisdiction refers to a court's "power" to hear a case. The Supreme Court has held that the APA itself does not provide subject matter jurisdiction. In other words, when bringing suit under the APA, plaintiffs must rely on a separate statutory provision to establish jurisdiction in court. A variety of statutes authorize jurisdiction in particular courts to review certain types of claims. For example, certain statutes permit review of particular agency actions in the U.S. Courts of Appeals, and some statutes may specify that review occurs in a particular federal appellate court. In addition, 28 U.S.C. Section 1331 bestows upon federal district courts "original jurisdiction of all civil actions arising under the Constitution, laws, or treaties of the United States." This grant of subject matter jurisdiction authorizes federal courts to hear claims arising under the APA as well as "nonstatutory" and constitutional claims. In addition to the requirement that a court exercise jurisdiction pursuant to the terms of a federal statute before adjudicating a case, the doctrine of sovereign immunity shields the United States from suits unless immunity has been waived by statute. Absent such a waiver, federal courts lack jurisdiction over lawsuits against the United States. A waiver of sovereign immunity will not be implied from legislative history or the background context of a statute; rather, it must be clearly expressed in the statutory text. Three primary statutes waive sovereign immunity, thereby permitting lawsuits against the United States in federal court under certain circumstances. First, the APA was amended in 1976 to permit individuals aggrieved by agency action to bring suit in federal court against the United States and government employees in their official capacity. However, this statutory waiver does not authorize money damages as a remedy. Second, the Federal Tort Claims Act (FTCA) permits suits to be heard in federal court for certain torts committed by agency employees in the course of their employment. In these cases, the United States is substituted as a defendant for the employee who allegedly committed the tort. Unlike the APA, the FTCA permits money damages as a remedy. Third, the Tucker Act permits suits against the United States for breach of contract and certain other monetary claims that do not arise in tort. Assuming a federal court has jurisdiction over a suit challenging an agency action, in order to challenge the actions of a federal agency, a plaintiff must also demonstrate that he or she posesses a legal right to seek judicial redress. A plaintiff will have a "cause of action" if he or she "is a member of the class of litigants that may, as a matter of law, appropriately invoke the power of the court." Various statutes explicitly provide such causes of action to enforce legal requirements against federal agencies. Absent a specific statutory framework creating a cause of action, the APA provides a general cause of action for individuals aggrieved by a "final agency action" if "there is no other adequate remedy in a court." There are other, less common bases for challenges to agency actions. In very limited situations, even lacking an express statutory cause of action, individuals may seek "nonstatutory" review of a agency action that is "ultra vires." In addition, when a federal official owes a plaintiff a "clear nondiscretionary duty," federal district courts and appellate courts may issue mandamus relief, which is an order compelling an official "to perform a duty owed to the plaintiff." However, the remedy is to be invoked only in "extraordinary circumstances" when "no adequate alternative remedy exists." Finally, the Supreme Court in Bivens v. Six Unknown Named Agents of Federal Bureau of Narcotics recognized a common law cause of action against federal officers for damages resulting from violations of constitutional rights. This remedy does not apply to federal agencies. In addition to statutory prerequisites for judicial review, certain constitutional and prudential considerations limit when courts will entertain a suit in a case challenging agency action. Plaintiffs must demonstrate that they have standing to challenge a federal agency's action and must also bring a lawsuit at the appropriate time. Article III of the Constitution defines the proper scope of the federal court jurisdiction as limited to adjudicating "cases" and "controversies." The Supreme Court has articulated several legal doctrines emanating from Article III, as well as various prudential considerations, that further limit the circumstances under which the federal courts will adjudicate disputes respecting federal agencies, such as standing, ripeness, and mootness. In particular, the doctrine of standing is a frequent barrier to plaintiffs challenging agency action. The Supreme Court has noted the important separation of powers principles that underlie the doctrine, emphasizing that while the judiciary is authorized to say what the law is, invalidation of congressional legislation or actions of the executive branch should not be taken lightly. Courts must, of course, vindicate individual rights, but the judicial power may not be harnessed into a monitoring role over federal agencies that should be conducted by Congress. In order to satisfy the constitutional requirement of standing, a plaintiff must "demonstrate that he has suffered 'injury in fact,' that the injury is 'fairly traceable' to the actions of the defendant, and that the injury will likely be redressed by a favorable decision." A plaintiff must assert more than a generalized interest in governance shared by all citizens and instead must have suffered an injury in fact or invasion of a legally protected interest that is (1) concrete and particularized and (2) actual or imminent. In addition, a "causal connection" between the alleged injury and challenged conduct is required, such that the injury is "fairly traceable to the challenged action of the defendant." Finally, it must be likely, rather than "merely speculative, that the injury will be redressed by a favorable decision." The doctrine of standing often operates to bar suits challenging agency action, for example, when plaintiffs seek to vindicate the public interest but have not suffered a concrete injury traceable to an agency action. A variety of factors also influence when it is proper for a federal court to adjudicate a challenge to agency action. Foremost among these are statutory deadlines and the doctrines of ripeness, mootness, and exhaustion. Many statutes authorizing judicial review of particular agency actions also impose filing deadlines for such challenges. Absent a specific statutory deadline, civil actions against the United States must be filed within six years of when the claim accrued or originated.