premise: Well, the issue before this Court, I hasten to say, as I said before, is only whether, once the Congress makes that judgment, it can ever change it retrospectively. The issue before this Court is not whether, in the future, a certain length of time would be appropriate.
hypothesis: Congress will change the decision of a judgement without considering when the decision was made.
reason: The statement is referring to the question if Congress can change their judgement after it is made, the time frame and if allowed is not clear.