Navy v. Egan (1988) acknowledges a due process protection but limits it to procedural due process, not review of the merits of the clearance determination (i.e., the due process protection does not extend to substantive due process.)

Subsequent cases (mostly at the Federal Circuit, I can’t find the Supreme Court getting involved much since) like Cheney v. DOJ (2007) and Cruz-Martinez v. DHS (2020) have developed what that requires.

For cases outside of government employment, though the decisions so far are only at the trial level, Perkins Coie LLC vs. DOJ (2025) and Zaid v. Executive Office of the President (2025) are worth checking out in this regard.