What is the "political question" rule?

The "political question" rule has two general applications or effects, one that is broad and commonly applied but rarely articulated as such, and one that is narrow but rarely applicable. Essentially the "political question" rule relates to the appropriate role of the judiciary in a tripartite system of government. Courts perform the judicial function, that is, they resolve cases and controversies before them and, in the process, interpret and apply the laws. (Massachusetts v. Mellon (1923) 262 U.S. 447, 488, 43 S.Ct. 597, 601, 67 L.Ed. 1078, 1085.) In doing so the courts may not usurp the governmental functions of the legislative and executive branches, and usurpation includes unwarranted intrusion into the roles of those branches. Thus it has been said: "The political question doctrine excludes from judicial review those controversies which revolve around policy choices and value determinations constitutionally committed for resolution to the [legislative and executive branches]." (Japan Whaling Assn. v. Amer. Cetacean Soc. (1986) 478 U.S. 221, 230, 106 S.Ct. 2860, 2866, 92 L.Ed.2d 166, 178.)