17 November 2013
What is the fewest number of Supreme Court justices to have decided a case?
Let's limit ourselves to the time period since the Supreme Court has had nine justices.
The answer is six--because six members of the Supreme Court constitute a quorum. But has the Supreme Court ever decided a case with just six justices?
At least twice. In 1948, the Supreme Court decided Shelley v. Kraemer with six justices. Similarly, in 1988, the Court decided Basic, Inc. v. Levinson with six justices. In each case, three justices recused themselves.
When the Court does not have a quorum, the effect is to affirm the lower court's ruling (with the same effect as upon affirmance by an equally divided Court). This has also happened (at least) twice. In 2008, four justices recused themselves from hearing American Isuzu Motors, Inc. v. Ntsebeza. The same result occurred in 1996, when four justices recused in United States v. Hatter (although Hatter made it back to the Supreme Court in 2001 and was ultimately decided with seven votes).
If I locate other such instances of cases involving bare quorum votes (six) or failure to constitute a quorum (five or less), I'll update them here.