FOR THOSE who think the process by which the two major political parties select their presidential candidates is a mess, the Supreme Court's decision last Wednesday offers a ray of hope. The court made it clear that the parties, not state governments, have the final say on how delegates to the national conventions are selected. That removes at least one barrier (or more accurately, excuse) that appears almost every time a major overhaul of the nominating process is proposed.

The court ruled, specifically, that the state of Wisconsin cannot bind delegates to the Democratic convention to vote for the winner of its preferential primary if that primary is conducted in a way that violates the national party's rules. Those rules now restrict participation in the nominating process to publicly proclaimed Democrats, while the Wisconsin primary is open to all -- Democrats, Republicans and independents. The decision means the state can continue to have its "open" primary if it wants to, but that the results are irrelevant (so long as the party's rules stay as they are) to either the selection of delegates or the instructions given them.

In a broader sense, the decision reaffirms the power of each national party to shape the nominating process much as it wishes. The justices quoted with approval a lower court decision saying that "a party's choice, as among various ways of governing itself, of the one which seems best calculated to strengthen the party and advance its interests, deserves the protection of the Constitution."

Using that sentence as a text, either national party could begin making some sense out of the jumble of primaries, conventions, mass meetings and so on that exhaust candidates and absorb vast quantities of money. The parties have the power to define more closely than they ever have who can participate in the selection of delegates and how those delegates are chosen. The parties can narrow the time span during which that selection is made. They may even be able to specify when primaries are to be held if the results are to select or instruct delegates.

All that is for the good. But there is an even more important theme in the court's decision. It is that the responsibility for the way a party selects its presidential candidate candidate rests squarely on the party itself. The recognition and acceptance of that simple fact by party officials would be the first step toward getting the nominating process under control.