In most fully argued and fully decided cases the justices vote at least three times. The first vote, cast in secret conference, determines whether the Court will hear the case. During the period of our study, about 75 percent of the cases heard by the Supreme Court came to the Court via a petition for a writ of certiorari (hereinafter cert), while the remaining cases, with few exceptions, arrived via a petition for a writ of appeal.

If the Court votes to grant cert, the case is scheduled for oral argument. After oral argument the justices again meet in conference to decide whether to reverse or to affirm the decision of the lower court. This vote is called the original vote on the merits. It is not a permanent vote, for any of the justices may change their vote at any time prior to the announcement of the Court's decision.

The final vote on the merits determines whether the decision below is, in fact, affirmed or reversed. This vote is cast by the justices during the course of their writing or joining the various opinions and can be ascertained by reading the published reports of these opinions.