In Hughes v. United States, the Supreme Court will revisit a thorny question: how to determine the precedential effect of decisions with no majority opinion. For four decades, the clearest instruction from the Court has been the rule from Marks v. United States: the Court's holding is "the position taken by those Members who concurred in the judgments on the narrowest grounds." The Marks rule raises particular concerns, however, when it is applied to biconditional rules. Biconditionals are distinctive in that they set a standard that dictates both success and failure for a given issue. More formulaically, they combine an if-then proposition (If A, then B) with its inverse (If Not-A, then Not-B).

Appellate courts on both sides of the circuit split that prompted the grant of certiorari in Hughes have overlooked the special features of biconditional rules. If the Supreme Court makes the same mistake, it could adopt a misguided approach that would unjustifiably create binding law without a sufficient consensus among the Justices involved in the precedent-setting case. This Essay identifies these concerns and proposes ways to coherently apply Marks to non-majority opinions that endorse biconditional rules.