Physics
The Concept of Justiciability in Federal Courts
Quick fact
Under the 'case or controversy' requirement, federal courts cannot issue advisory opinions or decide hypothetical disputes—even if the issue is legally important—unless there is an actual, ongoing injury to a specific party.
Why this is interesting
Can the Supreme Court refuse to decide a question of national importance just because the timing is wrong? In fact, it does so all the time—through the doctrine of justiciability.