Wiktionary
n. (context legal English): The ability of a subject matter to be evaluated and resolved by a court.
Wikipedia
Justiciability concerns the limits upon legal issues over which a court can exercise its judicial authority. It includes, but is not limited to, the legal concept of standing, which is used to determine if the party bringing the suit is a party appropriate to establishing whether an actual adversarial issue exists. Essentially, justiciability in American law seeks to address whether a court possesses the ability to provide adequate resolution of the dispute; where a court feels it cannot offer such a final determination, the matter is not justiciable.
Usage examples of "justiciability".
Court in a matter of that gravity, we would whittle the concept of justiciability down to the stature of minor or conventional controversies.