The First Amendment bans any law "abridging the freedom . . . of the press," but newspaper owners and government officials have been at loggerheads for at least a half-century over whether or not that prohibition curbs the application of business regulations to publishers.

In 1937, the Supreme Court said that the National Labor Relations Act could apply to the Associated Press; in 1951, the justices said that publishers seeking subscribers get no special protection against a city's blanket ban on door-to-door solicitation; in 1969, the high court reaffirmed that the antitrust laws apply to journalistic enterprises. The newest battle over the issue is being fought in Arlington County.

Four newsletter publishers whose main offices are in Arlington are challenging the county's demands that they pay a business license fee.

They have been paying the tax under protest for years, although this year one of the plaintiffs, Pasha Publications, has refused to honor the tax bill.

At the heart of the dispute is the "press exemption" written into the Virginia statute that authorizes counties to impose license fees on business operations.

That statute specifically bans a license tax for "the privilege or right of printing or publishing any newspaper, or for the privilege or right of operating or conducting any radio or television broadcasting station."

Arlington Revenue Commissioner Geraldine M. Whiting reads that provision as applying only to general-circulation publications, and classifies newsletter publishers as retail merchants, instead.

Whiting read through such publications as KCI Communications' "Tax Angles" and "International Investment Letter," and concluded that the articles were not varied enough or of enough appeal to a general reader for the company to qualify as a newspaper publisher. The same narrow focus is true of all the publishers in the suit.

Pasha, for instance, puts out "Coal Outlook," "Synfuels Week" and "Military Space." Washington Business Information publishes "Devices & Diagnostics Letter" and "Government Procurement Newsletter." The number of such specialized publications is growing rapidly.

Frederick D. Goss, editor of the newsletter published by the Newsletter Association, estimates that there are now close to 4,000 on the market, twice the number of a decade ago and eight times the total in 1965. And that just counts the output of commercial publishers, not the thousands of other newsletters put out by nonprofit or membership organizations.

It is unjust for the county to give the press exemption to some publishers and not to others, the newsletter companies say. But beyond that, they insist that the tax is unconstitutional because it "directly burdens the exercise of the rights of freedom of speech and press."

And in addition, they argue that the very way that Whiting went about deciding on whether to impose the tax -- looking into the content of the publications -- pressures them into making changes in the format or content of their publications to escape the government licensing fee. And they call that just the kind of pressure that the First Amendment is supposed to forbid.

The county insists that it is acting well within its authority, and has moved to have the case thrown out of court. A hearing on that motion is expected later this month.

But the issue is less clear-cut than it might have been when the policy of taxing newsletters was begun.

The Supreme Court two years ago rewrote the rules on how to square taxing authority with the First Amendment, and it was that decision that spurred the publishers to bring the current litigation.

The rules that were rewritten were laid down in 1936, when the high court struck down a 2 percent tax imposed by Louisiana on the advertising revenue of all newspapers with a weekly circulation of more than 20,000. The tax affected only 13 of the 124 publishers in the state at that time, but 12 of those 13 had editorialized at length against then-U.S. Sen. Huey Long. The justices suggested that the real purpose behind the advertising tax was the legislators' desire to punish the outspoken newspapers; ever since, that ruling has been interpreted as telling lower courts to look at the motivation behind any taxes that hit some parts of the press but not others.

Under that standard, it might have been hard to fight the Arlington County policy, for none of the plaintiffs accuse the county board of an animus against newsletters.

But in the 1983 ruling, the justices called unconstitutional a Minnesota tax that did not appear intended to censure outspoken newspapers. The state imposed a "use tax" on paper and ink consumed in producing newspapers and magazines, but the tax applied only to purchases that totaled more than $100,000 annually. The tax cost the Minneapolis Star & Tribune Co. more than $500,000 a year, but cost few other publishers anything. The justices said that singling out the press for a special tax is suspect under the First Amendment, and that a structure that hits some publishers hard and exempts others entirely is even worse.

The newsletter publishers think that describes what is happening in Arlington.