The U.S. Supreme Court case Edwards v. Vannoy, Warden (2020) revolved around the retroactive application of a previous ruling that juries must be unanimous to convict defendants in serious criminal trials. The petitioner, Thedrick Edwards, was convicted by a non-unanimous jury in Louisiana and sought relief based on the 2020 Ramos v. Louisiana decision which invalidated non-unanimous convictions as unconstitutional under the Sixth Amendment's right to trial by jury clause. However, the court ruled against Edwards with a 6-3 majority stating that new procedural rules do not apply retroactively to cases already final on direct review according to Teague v Lane precedent set in 1989; thus denying him post-conviction relief.

In the dissenting opinion for Edwards v. Vannoy, Justice Elena Kagan, joined by Justices Stephen Breyer and Sonia Sotomayor, argued that the majority's decision to overrule precedent was unjustified and harmful. They contended that Ramos v. Louisiana (2020), which held that a state criminal conviction cannot stand if not based on a unanimous jury verdict, should apply retroactively on federal collateral review because it is a watershed rule of criminal procedure implicating fundamental fairness and accuracy in criminal proceedings. The dissent criticized the majority’s abandonment of the “watershed” exception to non-retroactivity as inconsistent with principles of stare decisis or respect for precedent. It also warned against undermining public trust in judicial authority by suggesting courts can change rules at will without regard for past decisions.