In deference to judicial federalism, the Supreme Court will not review a case that has been decided by a state court when the decision is based on “independent and adequate” state legal grounds. However, determining the legal basis of ambiguously worded state court decisions has been a vexing problem for the Court. In Michigan v. Long (1983), the Court established a new rule for determining whether a state court decision rests on state or federal grounds. The Court held that when a state court decision discussed both state and federal law, but was not clear about which was controlling, the Court would presume that the decision was based on federal law, unless the state court provided a “plain statement” to the contrary.
The Long rule replaced a variety of approaches that the Court previously had used to determine the legal foundation of ambiguously worded state court decisions. These included requesting clarification from state courts, reviewing state court decisions itself, or simply dismissing the case. One goal of the Long rule, then, was to bring consistency to the criteria used by the Court in determining the legal basis of state court decisions.
Writing for the majority, Justice Sandra Day O’Connor argued that the Long rule served the interest of judicial federalism because it provided state courts the opportunity to develop their own law as the basis for their decisions. State courts would only have to issue a statement that their decisions rested on state law to immunize them from federal court review. However, the Court also signaled that it would take jurisdiction over any cases in which state courts failed to clarify the legal basis of their decisions. Because state courts often fail to issue plain statements, under Long the Court has expanded the range of cases that it defines as based on federal law compared to earlier approaches. Some critics have suggested that the Long rule has promoted conservative policies in areas such as criminal defendant rights because state courts are reluctant to expand rights under state law given the general unpopularity of such decisions, at the same time that the federal courts have scaled back their protections under federal law.
Shirley S. Abrahamson and Diane S. Gutmann, “The New Federalism: State Constitutions and State Courts,” Judicature 71 (1987): 88–99; and G. Alan Tarr, ed., Constitutional Politics in the States: Contemporary Controversies and Historical Patterns (Westport, CT: Greenwood Press, 1996).