The Supreme Court maintained that the federal courts will hear only genuine cases and controversies and will not give advisory opinions.
Very early in its history, the Supreme Court decided that the fundamental principle that courts should hear only genuine conflicts between parties (or cases and controversies) meant that the Court could not give advisory opinions. Muskrat v. United States is an almost classic attempt to bring a mock case or a friendly lawsuit between parties before the Supreme Court for the purpose of getting an advisory opinion. Congress had passed legislation affecting Native Americans and sought to discover whether it was constitutional. Congress specified that the U.S. government would be represented by the attorney general and that the Native Americans would be represented by counsel paid for by the U.S. Treasury. The Court, down to seven members because Justices Willis Van Devanter and Lucius Q. C. Lamar did not participate, rendered a unanimous decision denying the Court’s jurisdiction; the opinion was written by Justice William R. Day.
Native American treaties
Santa Clara Pueblo v. Martinez
Talton v. Mayes