Self imposed limitation on its power.  Court declines to entertain issues that are political in nature.
Political question doctrine seems to be a mesh of 2 principles:
1. Separation of powers: as a constitutional matter, the court will not decide matters which it concludes are committed by the Constitution to other branches of govt for decision.
2. Prudential concerns: court concludes that it is unwise, even if not strictly unconstitutional, for it to decide.
Apportionment cases are justifiable under the 14th Amendment but not under the Guaranty Clause in Article IV – 4