TO KEEP IT tightly secret, the State Department classified a list of 400 American meatpacking plants that European inspectors say fail to meet their standards. Publication of such a sensitive list, the department feels, would threaten national security. After all, if the American public began to form doubts about the basic integrity of the national supply of sausage and pigs' knuckles, the panic might easily spread to lamb and chicken. From there it could even affect public faith in the hamburger. The State Department was quite right to classify that list of packers, wouldn't you agree?

Perhaps you wouldn't. The case begins with the rigorous, not to say prissy, sanitation rules that the European Economic Community imposes on packers who want to sell in Europe. Those rules are to be applied to American packers next fall, and the European inspectors were here to have a look at their facilities. The EEC's agriculture program supports the price of meat the same way that the American program supports corn and wheat. The EEC has its prices too high, for reasons familiar to any U.S. senator, and the rising costs of Europe's gigantic agricultural surpluses push the EEC into one financial crisis after another. Most governments, including the EEC, occasionally resort to bureaucratic ingenuity to keep out unwanted imports by invoking some ostensibly unrelated standard.

When the European inspectors produced the list of packers who failed their inspection, the U.S. Department of Agriculture immediately foresaw a wave of anxiety -- and falling meat sales -- if it became public. It went to the State Department, which, for diplomatic reasons, wanted to avoid further inflammation of the long and testy quarrel over transatlantic agricultural trade. The political people at the EEC saw the point and agreed that it would be much better not to let the list out. The State Department hastily stamped it classified on national security grounds.

So a nasty little row has been averted, but at a substantial cost. A degree of injury has been inflicted -- nothing fatal, but the bruise is visible -- on people's right to know what their various governments are up to. Beyond that, it is a notorious failure of the American security system to attempt to cover too much. There have been repeated references to that in the spy prosecutions that have become an unhappy staple of the news. The American system, the security specialists warn, keeps trying to classify too much paper with too many people and as a result sometimes loses genuinely important secrets in its endless scramble to control marginal stuff that has been stamped merely to avoid policical embarassment. In which category would you put the list of the 400 meatpackers?