On April April 23, the Supreme Court is going to hear the appeal of the federal district court decision throwing out the Gramm-Rudman trigger mechanism. The court doesn't say when it will decide a case, but everyone involved expects a decision by early July, before the court's summer recess. This is being billed by commentators as a very rapid appeal process. We ask: What is so rapid about it? Why not decide this case sooner?

To put the question is not to underestimate either the seriousness or the difficulty of the issue. But the court can hear cases and decide them more quickly when it thinks it should, and it has done so in the recent past. Such cases tend to revolve around issues of heightened political sensitivity and, thus, urgency. The Iranian assets cases of 1980, the Pentagon papers case in 1971 and the steel seizure case in 1951 were all briefed, argued and decided in very short order. None of these stands on all fours, as the lawyers say, with the Gramm-Rudman case. But in all three it was asserted that policy would be gravely affected if the court did not act almost at once.

Something very similar can surely be said of the challenges made to Gramm-Rudman by Rep. Mike Synar (D-Okla.) and certain government employees' unions. It is true that the trigger mechanism that was outlawed by the district court has a back- up that can be invoked. And it is also true that Congress has the constitutional power to enact a budget resolution and, for that matter, a balanced budget even while awaiting a court decision.

But important deadlines pass before the court hears argument and before it is likely to issue a decision. Congress is supposed to complete action on a budget resolution April 15. The House Appropriations Committee is supposed to finish work on regular appropriations bills June 1. Congress is supposed to complete action on a reconciliation bill June 15. The House is supposed to complete action on regular appropriations bills June 30. Some of these deadlines may be missed. But they are supposed to be met. Negotiation positions and bargaining, showdowns and votes will be affected by the case on appeal to the Supreme Court. The most important questions of spending, and perhaps taxing, will be skewed pending the court's decision. Decisions may be postponed or delayed. Results affecting the government's whole budget will be affected.

The distortion produced by the overhanging lawsuit would be avoided if the court acted more quickly. It can be said in the court's behalf that it has adopted the schedule by the parties on both sides of this case. But it is within the court's power to set earlier deadlines. Of course the issues are hard, and need careful deciding. But, with so much at stake, it would be much better if the ruling could come much sooner.