cf.

In March 1992, Alfonso Lopez, Jr., a twelfth-grade student at Edison High School in San Antonio, Texas, arrived at school carrying a concealed .38-caliber handgun and five bullets. Acting on an anonymous tip, school authorities confronted Lopez, who admitted possessing the weapon. Local police arrested him and charged him under Texas law with firearm possession on school premises. The following day, state charges were dismissed after federal agents charged Lopez with violating the Gun-Free School Zones Act of 1990. A federal grand jury indicted him on one count of knowing possession of a firearm at a school zone. Lopez moved to dismiss the indictment, arguing that the statute exceeded Congress's power to legislate control over public schools. The district court denied the motion, concluding that the statute was a constitutional exercise of Congress's power to regulate activities affecting commerce because the business of schools affects interstate commerce. After a bench trial, the court found Lopez guilty and sentenced him to six months' imprisonment and two years of supervised release. Lopez appealed to the Court of Appeals for the Fifth Circuit, which reversed the conviction, holding that the statute was beyond Congress's power under the Commerce Clause. The Supreme Court granted certiorari to review the case.

In early 1973, Mrs. Inez Moore received a notice of violation from the city of East Cleveland. The notice stated that her grandson John Moore, Jr., was an illegal occupant of her home. It directed her to comply with the housing ordinance. Mrs. Moore lived in her East Cleveland home together with her son Dale Moore, Sr., and her two grandsons Dale Moore, Jr., and John Moore, Jr. John came to live with her after his mother's death when he was less than one year old. When she failed to remove John from the home, the city filed a criminal charge against her. Mrs. Moore moved to dismiss the charge. She claimed that the ordinance was constitutionally invalid on its face. Her motion was overruled. Upon conviction she was sentenced to five days in jail and a $25 fine. The East Cleveland ordinance limited occupancy of a dwelling unit to members of a single family. The ordinance defined family to include only a husband or wife of the nominal head of the household, unmarried children of the head or spouse provided they have no children residing with them, a parent of the head or spouse, or not more than one dependent child of the head or spouse along with that child's spouse and dependent children. The Ohio Court of Appeals affirmed the conviction after giving full consideration to her constitutional claims. The Ohio Supreme Court denied review of the case. The United States Supreme Court noted probable jurisdiction of her appeal.

In 1965 New York City enacted the Landmarks Preservation Law, which created an eleven-member Landmarks Preservation Commission and authorized it to designate buildings at least thirty years old that possess special historical or aesthetic interest. The law required owners of designated landmarks to obtain Commission approval before altering exterior architectural features and imposed an affirmative duty to keep those features in good repair. In August 1967 the Commission designated Grand Central Terminal a landmark and the city tax block it occupies a landmark site; the Board of Estimate confirmed the designation the following month. Penn Central Transportation Co. and its affiliates owned the Terminal, an eight-story Beaux-Arts structure completed in 1913 that served as the main station for the New York Central and Harlem lines. On January 22, 1968, Penn Central entered a fifty-year renewable lease with UGP Properties, Inc., under which UGP agreed to construct a multistory office building cantilevered above the Terminal and to pay Penn Central at least three million dollars annually after construction. Penn Central and UGP submitted two plans prepared by architect Marcel Breuer: Breuer I, a fifty-five-story tower resting on the Terminal roof, and Breuer II Revised, a fifty-three-story building that would have removed part of the 42d Street facade. After four days of hearings at which over 80 witnesses testified, the Commission denied this application as to both proposals. Penn Central filed suit in New York Supreme Court, Trial Term, seeking a declaratory judgment, injunctive relief, and damages for a temporary taking. The trial court granted the injunctive and declaratory relief. The Appellate Division reversed, holding that Penn Central had failed to prove deprivation of all reasonable beneficial use. The New York Court of Appeals affirmed, concluding that the Terminal could still earn a reasonable return and that transferable development rights provided significant compensation. The Supreme Court noted probable jurisdiction.

Tompkins, a citizen of Pennsylvania, was injured on a dark night by a passing freight train of the Erie Railroad Company while walking along its right of way at Hughestown in that State. He claimed that the accident occurred through negligence in the operation or maintenance of the train. He asserted that he was rightfully on the premises as a licensee because he was on a commonly used beaten footpath which ran for a short distance alongside the tracks. He further alleged that he was struck by something which looked like a door projecting from one of the moving cars. To enforce that claim he brought an action in the federal court for southern New York, which had jurisdiction because the company is a corporation of that State. The Erie insisted that its duty to Tompkins was no greater than that owed to a trespasser. It contended, among other things, that its duty to Tompkins, and hence its liability, should be determined in accordance with the Pennsylvania law; that under the law of Pennsylvania, as declared by its highest court, persons who use pathways along the railroad right of way are to be deemed trespassers; and that the railroad is not liable for injuries to undiscovered trespassers resulting from its negligence, unless it be wanton or wilful. Tompkins denied that any such rule had been established by the decisions of the Pennsylvania courts. He contended that, since there was no statute of the State on the subject, the railroad's duty and liability is to be determined in federal courts as a matter of general law. The trial judge refused to rule that the Pennsylvania law precluded recovery. The jury brought in a verdict of $30,000. The judgment entered thereon was affirmed by the Circuit Court of Appeals, which held that it was unnecessary to consider whether the law of Pennsylvania was as contended, because the question was one not of local, but of general, law and that upon questions of general law the federal courts are free, in the absence of a local statute, to exercise their independent judgment as to what the law is. Because of the importance of the question whether the federal court was free to disregard the alleged rule of the Pennsylvania common law, the Supreme Court granted certiorari.