And now the BBA

In my gun-metal 12-drawer filing cabinet (in easy reach if I swivel from my roll-top desk) I don't even have an entry on ''Prohibition.'' I know because I just looked. And yet Prohibition was the hottest political topic of its day and entered the United States Constitution, just as the proposal to require a balanced budget may enter as an amendment. If the new law passes, it will be the ''BBA,'' I suppose, for balanced budget amendment.

In just under 200 years there have been only 26 amendments to the Constitution, which indicates that the august document is not something to be altered lightly. The new amendment, if adopted, will be Amendment XXVII. The count is a little awkward, perhaps, because two previous amendments cancelled each other out. The 18th Amendment was proposed in December 1917 after a century of agitation, and was ratified, with a boost from the war, Jan. 16, 1919. After Congress sent it to the state legislatures for approval, the membership of the upper chambers of the respective bodies voted 84.6 percent ''dry,'' and the lower chambers 78.5 percent. The ''dry'' sentiment seemed overwhelming and yet the law didn't work. The proposal for repeal (Amendment XXI) passed Congress in February 1933, and was ratified Dec. 5, 1933. Prohibition lasted about 14 years.

Now comes the test of a new constitutional amendment. It writes the aspiration of a balanced budget into the basic law. There are various exceptions and modifications to the rules it lays down for future legislatures, but its proposal is more than a simple statement of an aspiration. It imposes requirements, and its reasoning is based on the Report of the Committee on the Judiciary (US Senate, July 10, 1981):

''...in large measure, the nation's economic problems are attributable to the Federal Government's persistent failure to balance its budget.''

Congress, which has passed the deficits, and the President, who is coping with one of the biggest deficits in history, are accordingly considering an amendment requiring a balanced federal budget. First impression is that it will pass. Don't do it! say a great many economists. Eighty of them in a statement recently said, ''We are unanimous in our conviction that such an amendment is not in the national interest.'' Gardner Ackley of the University of Michigan, a former chairman of the President's Council of Economic Advisers, 1964-68, gave representative views:

''Simply because deficits at the wrong time can be extremely dangerous is no reason to prohibit deficits at all times - or even to make them available only if three-fifths of the members of each House specifically so approve. Twenty-one stubborn senators, or 112 members of the House of Representatives, might threaten severe economic and political damage to the national welfare.''

Don't get so agitated, reply advocates of the amendment. Substantial loopholes have been included. Yes, we agree a balanced budget may be dangerous at times - like the Great Depression under Herbert Hoover which raised unemployment to 25 percent. But the proposed amendment is flexible; wars are excepted; there is plenty of leeway.

Mr. Ackley isn't satisfied. Support for the BBA, he declares, ''appears mainly to reflect an incoherent public revolt - the dimensions of which are uncertain - against taxes, government spending, and budget deficits.''

Mr. Ackley and others like him may be ignored but they won't be cowed. Yes, he agrees, the ''glaring loopholes in the language of the proposed amendment might well prevent it from having any significant effect on government spending, taxes, or deficits.''

But, so what? ''This fact,'' he adds warmly, ''is hardly an argument for its adoption; if anything, it is another strong reason not to clutter up our Constitution with unwarranted and indefensible economic nonsense.''