The provisions of the U.S. Constitution setting out the powers of the Federal judiciary, define those powers in using two different but related words "cases" and "controversies". See U.S Constitution, Article III, section 2. In framing judicial authority these words also represent limits. The Federal Courts do not, under Article III, have the power to resolve legal questions that do not arise out of an actual dispute between real parties. In some states, by contrast, the highest courts have jurisdiction to hear and provide advisory opinions on questions submitted by the state legislature. A statute attempting to give such jurisdiction to the Federal courts would run into the Constitutionally based requirement of a "case" or "controversy". For examples of cases in which the Supreme Court has found this critical element lacking, see, e.g., Arizonans for Official English v. Arizona, 520 U.S. 43 (1997) and Renne v. Geary, 501 U.S. 312 (1991).

This basic limit on judicial power has led to more specific limiting doctrines, including: mootness, ripeness, and standing.