Separation of powers.
The Supreme Court balances several pressures to maintain its roles in national government. It seeks to be a co-equal branch of government, but its decrees must be enforceable. The Court seeks to minimize situations where it asserts itself superior to either President or Congress, but federal officers must be held accountable. The Supreme Court assumes power to declare acts of Congress as unconstitutional but it self-limits its passing on constitutional questions. But the Court's guidance on basic problems of life and governance in a democracy is most effective when American political life reinforces its rulings.
Justice Brandeis summarized four general guidelines that the Supreme Court uses to avoid constitutional decisions relating to Congress: The Court will not anticipate a question of constitutional law nor decide open questions unless a case decision requires it. If it does, a rule of constitutional law is formulated only as the precise facts in the case require. The Court will choose statutes or general law for the basis of its decision if it can without constitutional grounds. If it does, the Court will choose a constitutional construction of an Act of Congress, even if its constitutionality is seriously in doubt.
Likewise with the Executive Department, Edwin Corwin observed that the Court does sometimes rebuff presidential pretensions, but it more often tries to rationalize them. Against Congress, an Act is merely "disallowed". In the executive case, exercising judicial review produces "some change in the external world" beyond the ordinary judicial sphere. The "political question" doctrine especially applies to questions which present a difficult enforcement issue. Chief Justice Charles Evans Hughes addressed the Court's limitation when political process allowed future policy change, but a judicial ruling would "attribute finality". Political questions lack "satisfactory criteria for a judicial determination".
