Well, there is the Ineligibility Clause in the Constitution (Article I, Section 6, Clause 2). But that only concerns the ineligibility of cross-serving in the legislative and executive&#x2F;judicial branches, iirc.<p>There&#x27;s nothing I can think of in the Constitution that prevents serving under the executive and judicial branches simultaneously. In fact, John Marshall did exactly that (Chief Justice &amp; Sec. of State, iirc).