Suitable for courts to hear and decide on the merits. If a case is not justiciable, the court must dismiss it.
The justiciability doctrines limit federal judicial power and include rules that the Supreme Court has crafted to determine (i) whether there is a sufficient “case or controversy” that the court may decide on under Article III of the Constitution; or (ii) whether there are prudential limits which bar courts from exercising judicial review. The doctrines encompass the prohibition against advisory opinions; standing; ripeness; mootness; and the political question doctrine.
Definition from Nolo’s Plain-English Law Dictionary
A matter which is capable of being decided by a court. Usually it is combined in such terms as: "justiciable issue," "justiciable cause of action," or "justiciable case."
The Supreme Court only hears cases that are justiciable; thus, it will not hear a case where the party bringing suit does not have standing (i.e., is not the proper party to bring the matter to the court).
“We have repeatedly recognized that what is required for litigation to continue is essentially identical to what is required for litigation to begin: There must be a justiciable case or controversy as required by Article III.” J. Ginsburg, Friends of the Earth, Inc. v. Laidlaw Environmental Services (TOC), Inc., 528 U.S. 167, 212 (2000).