By some measures, United States v Booker is the most important case the Seventh Circuit has decided in decades. On the heels of the Supreme Court’s decision in Blakely v Washington to invalidate Washington State’s mandatory sentencing guidelines, the Seventh Circuit held that the Federal Sentencing Guidelines were constitutionally infirm as well. Prompted by the Seventh Circuit, the Supreme Court granted certiorari and struck down the Federal Sentencing Guidelines six months later in United States v Booker, uprooting the decades-old system of determinate federal sentencing. Booker’s reverberations continue to be felt, as federal courts struggle with the newly permissive sentencing regime and the Supreme Court decides case after subsequent case in an effort to iron out the wrinkles caused by its decision.