Flast v Cohen Quote re case & controversy

The jurisdiction of federal courts is defined and limited by Article III of the Constitution.  In terms relevant to the question for decision in this case, the judicial power of federal courts is constitutionally restricted to "cases" and "controversies." As is so often the situation in constitutional adjudication, those two words have an iceberg quality, containing beneath their surface simplicity submerged complexities which go to the very heart of our constitutional form of government. Embodied in the  words "cases" and "controversies" are two complementary but somewhat different limitations. In part those words limit the business of federal courts to questions presented in an adversary context and in a form historically viewed as capable of resolution through the judicial process. And in part those words define the role assigned to the judiciary in a tripartite allocation of power to assure that the federal courts will not intrude into areas committed to the other branches of government. Justiciability is the term of art employed to give expression to this dual limitation placed upon federal courts by the case-and-controversy doctrine.

Justiciability is itself a concept of uncertain meaning and scope. Its reach is illustrated by the various grounds upon which questions sought to be adjudicated in federal courts have been held not to be justiciable. Thus, no justiciable controversy is presented when the parties seek adjudication of only a political question, when the parties are asking for an advisory opinion, when the question sought to be adjudicated has been mooted by subsequent developments, and when there is no standing to maintain the action.

Flast v Cohen, 392 U.S. 83 (1968)