Professor Krishnakumar has an interesting post at Concurring Opinions analyzing the use of the Rule of Lenity on the Roberts Court:

In their Legislation casebook, William Eskridge, Philip Frickey, and Elizabeth Garrett observe that between 1984 and 2006, the Supreme Court cited the rule of lenity in just over one-fourth of its cases interpreting criminal statutes and agreed with the government’s interpretation in over 60% of those cases. I thought it would be interesting to see how those figures compare to the still-nascent Roberts Court’s cases interpreting criminal statutes.

Between February 2006 (when Justice Alito joined the Court) and the end of June 2009 (Justice Souter’s last day on the Court), the Roberts Court decided twenty-five cases that involved at least some interpretation of a criminal statute. In fourteen of those twenty-five cases (56%), the Court interpreted the statute in a manner that favored the defendant. In only six of the cases did the Court reference the Rule of Lenity—four times in dissent, one time in both the plurality opinion and the concurring opinion providing the fifth vote, and one time in a concurring opinion alone.

Interestingly, Scalia and Stevens were the Justices most likely to reference the rule of lenity, while Justices Alito and Kennedy have not joined a single case invoking the rule. Krishnakumar concludes that the Roberts Court use of the rule of lenity mirrors the usage during the Rehnquist Court.