"Judges often invoke the separation of powers to limit their own authority, to put certain classes of executive action off-limits from judicial review, or..."

"... to shape and constrain the remedies they provide. That has been true for as long as we have had courts and judicial review.... As a matter of separation of powers, the courts may themselves decide that courts ought not to be the ones to decide a given issue.... To date, all the Trump administration’s responses in court have embodied appeals to these principles. In response to a recent temporary restraining order that seemingly barred all political appointees at the Treasury Department from access to certain internal information, the administration argued in a filing that the work of executive agencies is overseen by the president, and 'a federal court, consistent with the separation of powers, cannot insulate any portion of this work from the specter of political accountability.' That was a straightforward legal appeal to the limits of judicial authority, made within a judicial proceeding as an argument under applicable law. Even where courts have jurisdiction to decide, it is always legally valid to argue that their decisions ought to respect the separation of powers...."

Writes lawprof Adrian Vermeule, in "JD Vance’s Tweet Is No Crisis/Judges also have an obligation to respect the separation of powers. Usually they do so" (Wall Street Journal, no paywall).