The Constitution imposes several qualifications for Congressional service, most notably in Article I, s2 & 3 (which sets out age, citizenship, and residency requirements). It also precludes members from Congress from serving in the executive or judicial branches through the Incompatibility Clause in Article I s6. This clause was designed to foreclose patronage and corruption, but also precludes a parliamentary-style of government in which office holders have both legislative and executive powers. Interestingly, the clause does not forbid simultaneous executive and judicial service, reflected by examples such as John Jay and John Marshall (both of whom served as Secretary of State while also sitting on the Supreme Court). Today such a practice would be viewed as constitutionally suspect.