Avitts (plaintiffs) filed suit against Amoco Production Co. and several other oil companies (defendants) in Texas state court. The plaintiffs and at least one of the defendants were citizens of the same state. The plaintiffs claimed that their property was damaged by the defendants’ activities in the West Hastings Field. In the original complaint, the plaintiffs asserted that the evidence would show that the defendants had violated “not only State law but also Federal law.” No other reference to violations of federal law was made in the original complaint or any of the numerous amended complaints. The plaintiffs later did mention the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the Oil Pollution Act of 1990 (OPA) in the Joint Pretrial Order (PTO) as a means for assessing the damages, but did not state a cause of action under either act. The defendants filed notice of removal to the United States District Court for the Southern District of Texas at the same time they moved the court for a more definite statement under Fed. R. Civ. P. 12(e). The motion for a more definite statement was denied, and the case was removed to federal court. The district court issued a preliminary injunction against the defendants, ordering them to complete an environmental study. The defendants were also ordered to pay $650,000 in interim costs and fees. The defendants’ appeals were consolidated in the United States Court of Appeals for the Fifth Circuit.