The Rule of Lenity

The “rule of lenity” “requires ambiguous criminal laws to be interpreted in favor of the defendants subjected to them.”

From Levin, Daniel and Stewart, Nathaniel, Wither the Rule of Lenity, Engage, November 16, 2009.  This is a claim or objection I have used from time to time, not always successfully.  Typically I’m using it as an argument regarding application of an R.C.M. or Mil. R. Evid., an argument by analogy I suppose.  Another way to express this would be that where there is an ambiguity the ambiguity should be construed against the writer.  Perhaps there is some hope?

In 2008, in United States v. Santos, the Supreme Court issued a plurality opinion holding that a key term in a federal money laundering statute was ambiguous and applied the rule of lenity to resolve the ambiguity in the defendants’ favor. The plurality involved just such a coalition of conservative and liberal Justices (Justices Scalia, Thomas, Ginsburg, and Souter; with Justice Stevens writing separately and agreeing that the rule should apply), raising the question of whether the rule may be entering a period of somewhat greater application…

Justice Scalia wrote the majority opinion in Santos.

Under a long line of our decisions, the tie must go to the defendant. The rule of lenity requires ambiguous criminal laws to be interpreted in favor of the defendants subjected to them.

This venerable rule not only vindicates the fundamental principle that no citizen should be held accountable for a violation of a statute whose commands are uncertain, or subjected to punishment that is not clearly prescribed. It also places the weight of inertia upon the party that can best induce Congress to speak more clearly and keeps courts from making criminal law in Congress’s stead.

When interpreting a criminal statute, we do not play the part of a mind reader. In our seminal rule-of-lenity decision, Chief Justice Marshall rejected the impulse to speculate regarding a dubious congressional intent. “[P]robability is not a guide which a court, in construing a penal statute, can safely take.” United States v. Wiltberger, 5 Wheat. 76, 105 (1820). And Justice Frankfurter, writing for the Court in another case, said the following:“When Congress leaves to the Judiciary the task of imputing to Congress an undeclared will, the ambiguity should be resolved in favor of lenity.” Bell v. United States, 349 U. S. 81, 83 (1955).

Slip op. at 6-7.