What rule do the justices follow when deciding whether to hear a case or not?

The Supreme Court decides to hear a case based on three major factors:

1. Whether the appeal came from the US Court of Appeals Circuit Courts or state supreme court and is in conflict with the decisions of other Circuits (circuit split);
2. Whether the case involves an important constitutional issue that has not yet been resolved; and
3. Whether the lower court's decisions may be wrong in light of the Supreme Court's opinions.

The justices then vote to determine whether they want to review the case. If four justices (the "rule of four") agree the case is worthy of the Court's time, they will grant certiorari.