Political question doctrine
Political question doctrine requires a court to abstain from a case or controversy that involve matters that must be, or can only properly be, handled by the other branches of government.
Examples include legal challenges to foreign policy or the military.
Doctrinally, political question doctrine embodies the Constitution's limitation of the "judicial power of the United States" to "cases" or "controversies." U.S. CONST. art. III. "It is therefore familiar learning that no justiciable 'controversy' exists when parties seek adjudication of a political question." Massachusetts v. EPA, 549 U.S. 497, 516 (2007) (global warming decision).
The criteria for application of political question doctrine was set forth in Baker v. Carr:
-  a textually demonstrable constitutional commitment of the issue to a coordinate political department; or  a lack of judicially discoverable and manageable standards for resolving it; or  the impossibility of deciding without an initial policy determination of a kind clearly for nonjudicial discretion; or  the impossibility of a court's undertaking independent resolution without expressing lack of the respect due coordinate branches of government; or  an unusual need for unquestioning adherence to a political decision already made; or  the potentiality of embarrassment from multifarious pronouncements by various departments on one question.
369 U.S. at 217. "To find a political question, we need only conclude that one [of these] factor[s] is present, not all." Schneider v. Kissinger, 412 F.3d 190, 194 (D.C. Cir. 2005).
For a recent and comprehensive restatement and application of political question doctrine, see El-Shifa Pharm. Indus. Co. v. United States, 607 F.3d 836, 841 (D.C. Cir. 2010) (en banc).