When it comes to international trade, the butter cookie is a David among the Goliaths of steel, color television and shoes.

And no one, not even the butter cookie makers themselves, would suggest the tiny industry has a big enough stone in its sling to knock off the steel industry as the world's most difficult trade problem.

Nevertheless, if U.S. and European trade officials could draw up a Christmas list of thorny issues they would like to see disappear, the rich little Danish-type butter cookie that comes in the shiny blue tin or foil-wrapped in the blue box would rank right up there with steel.

In a world consumed by the trade problems of giant industries, it is not unexpected that the case of the butter cookie would receive little public attention.

But by Dec. 28, the U.S. Treasury must decide whether to slap special, countervailing duties on the butter cookies this nation imports from Denmark.

And the decision threatens to have a wide-ranging impact, not only on the narrow concerns of the butter cookie industry (in fact, for all practical purposes only one American company makes the expensive kind of cookie in question), but on the complicated series of subsidies Europe uses to make its "Common Agricultural Policy" work as well as on the four-year-old multi-lateral trade talks that finally seem to be getting untracked in Geneva.

It's not that the butter cookie industry is a big one. While the United States imports hundreds of millions of dollars of color television sets a year, it buys little more than $6 million of Danish butter cookies (the American Deer Park Baking Co. makes the remaining $2 million).

There are lots of "Danish" assortments around, but they are usually less expensive and, to hear cookie buffs tell it, are made with interior ingredients such as shortening instead of butter. The key to the high quality cookie is the word "butter" not the word "Danish" and the rich, ingredient-pure morsels sell for about $4 a tin these days.

When Deer Park - located in Hammonton, N.J. - began to market aggressively its butter cookie about eight years ago, sales took off, according to vice president William Crothers.

But recently, as the price of U.S. butter has soared, sales that had doubled every year leveled off. "We cannot compete with the Danes" on price because the European Community's common agricultural policy subsidizes the butter the Danish cookie makers use, Crothers said, buying from low-priced EEC stocks.

The Treasury also found that the European Community gave export rebates on the eggs, flour and sugar the Danish cookie makers used.

The Treasury already has decided that the rebates Danish manufacturers get as well as access to low-priced butter are indeed "bounty or grant" that the nation's countervailing duty laws prohibit. By Dec. 28 the Treasury must decide to either slap on a duty equivalent to the subsidy or give imported Danish butter cookies a waiver from the law.

Danish cookie makers have asked the Treasury for such a waiver arguing that they qualify under the terms of the 1974 trade act because:

There is little or no effect on domestic U.S. cookie makers. In a brief submitted to the Treasury last September, the Danish Cake and Biscuit Alliance sniffs that there is no one - except for the Danes - producing cookies "which can claim a quality and price equal to the Danish butter cookies. At most there is only one U.S. company, hardly an industry, which produces a product even roughly comparable to Danish butter cookies."

It appears that the Geneva negotiations will come up with an agreement on non-tarriff barriers trade.

Imposition of a countervailing duty would seriously harm the trade negotiations.

A top Treasury official concedes that the Danish cookie case can be viewed as either a small decision affecting a minimal $6 million in imports or a decision that goes right to the heart of the complex subsidies that make the European Community's common agricultural policies work.

Both the U.S. and the Europeans would prefer it if the United States did not have to make a ruling in the matter, but Deer Park, which claims to have a product equal to the quality of the Danish model, doggedly pursued its countervailing duty case.

If the Treasury does impose countervailing duties (in 1975 it saw fit not to in a similar case, that of table quality Emmenthaler cheese from Switzerland), Europeans are fearful that it could trigger similar complaints against a host of processed foods the Europeans ship here every year.

For the Treasury has determined that the subsidy is not on the product in question - as it has in all earlier cases where it has determined a need to slap on countervailing duties - but on an ingredient. Million of dollars of other products - from German wines with subsidized sugar in them to hard candies from Great Britain - could suffer the same fate.

But these matters of international diplomacy don't sway Crothers. Despite all the Danish talk of being so much more expensive than Deer Park, noted Crothers, his New York distributor just priced tins of the supposedly more expensive Danish cookies at $1.25, he said, "I can't turn one out of here for less than $2," he argued.

"All I want is a fair shake," said Crothers. "Any produce that is subsidized by a foreign government should have the amount of that subsidy added to its price by a countervailing duty.