The U.S. Supreme Court took an important “first step” in adopting a formal ethics code on Monday, reformers say, but the lack of any mechanism to enforce it has left them wanting more.

The court’s new code of conduct—signed by all nine justices—largely mirrors the code that has long applied to all lower federal court judges, with a handful of tweaks to account for what the justices called the “unique institutional setting” of the Supreme Court.