Writing letters to the government is nothing new. It is an honorable way to exercise freedom of expression in our democracy and may influence legislation. Sometimes, though, the letters are not so individual nor the intent so honorable.

A case in point. The Bureau of Alcohol, Tobacco and Firearms announced in January that it was considering proposing warning labels on spirits, wine and beer to alert expectant mothers to the possibility that drinking alcohol may harm the unborn child.

The issue is a touchy one. Government officials, among them Dr. Donald Kennedy, chief of the Food and Drug Administration, appear to accept the theory of "fetal alcohol syndrome." Other scientists and the wine and spirits industry contend there has not been spirits industry contend there has not been sufficient research to isolate alcohol as the culprit in the birth of about 1,500 babies each year who are mentally or physically retarded.

During a two-month period for comment on what is not even yet a formal proposal, 2,832 letters were received by BATF. The volume was characterized as "very heavy" by a bureau spokesman. A reading of the comments - available to the public - indicates that the outpouring of opinion on both sides was not entirely spontaneous.

Nearly 200 letters, almost all advocating warning labels, were sent to BATF before the request for comments had even appeared in the Federal Register.

An anonymous letter from an employe of a Denver distributor of Gallo wines accused the giant wine firm of "soliciting the employes to go on a letter-writing campaign against the proposal . . ." The letter was accompanied by five pages of suggested answers to questions posed by BATF and a seven-point procedure that said, in part: "Correspondence should be single copy only . . . and should make no reference to Gallo" and "Field personnel should attempt to maintain a list of all individuals sending correspondence."

A Gallo spokesman acknowledged this past week that the material had originated from a Gallo official, but said the official had acted on his own, without approval from corporate headquarters in Modesto, Calif., and the material had been distributed only at the Denver subsidiary.

According to the spokesman, Gallo had intended simply to inform employes and their wine-drinking friends that the issue had been raised, and they were free to comment on it. This step was taken, he said, with the encouragement of the Wine Institute, the California industry's trade association.

A Wine Institute official said member firms had been asked to participate, "but only when we became aware there was a concerted effort on the other side." A spokesman for the Distilled Spirits Council of the U.S. said, "We've let our people know. The warning label advocates have let people know too. It's an emotional issue on both sides."

Dr. Ernest Nobel, who heads the National Institute for Alcohol Abuse and Alcoholism within the Department of Health, Education and Welfare, issued a "caution to the nation" about fetal alcohol syndrome last year and feels he influenced HEW's Kennedy into calling for warning labels. BATF, a division of the Treasury Department, is charged with regulating labels for alcoholic beverages. Officials there claim they were given no prior warning of Kennedy's action.

Since Kennedy's statement, BATF put forth its "notice of proposed rulemaking," asking for opinions on what type of label might be adopted, what its impact and effect on pregnant women would be, possible alternatives to a label, and information on medical research on the subject. A Senate hearing on the subject was held at the end of January.

BATF will evaluate the letters and many then propose a label regulation. Or the bureau may argue that the move is premature and await further evidence from research projects or the formulation of a national policy "on alcohol use and disuse."

Nobel argues the evidence already available is "extremely compelling." Labeling, he believes, "will not do it all. But it is one step. Progress will be made only through a combined approach" involving physicians, government and educational institutions. "There are industrial interests that people feel need to be protected," he said, "but we are moving into a different age. It's a question of the quality of life."

Some of the citizen replies don't accept that premise. A woman writing from Florida concluded her negative response, "I am also tired of our government telling me what's good or bad for me." Another woman, from Texas, stated, "I enjoy a glass of wine - it's never hurt me, not even when I was pregnant."

It doesn't take an advocate to realize that writer of the second letter has missed the point of the proposal.

That wine is the subject of many comments should come as no surprise. Table wine is not highly alcoholic, has established itself in this country as a beverage of social and cultural significance and its use in moderation has considerable support within the medical community.

John DeLuca, president of the Wine Institute, has organized what might be called a spirited defense of wine and attacked the labeling proposal on several grounds. Among them:

Evidence is lacking that labels would improve a situation that involves only a minuscule percentage of the consuming public; that manufacturers would be forced to undertake a costly program that would project a negative image about wine, that it is a product considered a beverage of moderation and deemed healthful by many physicians; that the warning would not reach those who bought alcoholic beverages by the glass in bars and restaurants.

DeLuca and others also raise the specter of something that has been tagged "neoprohibitionism." The implication is that while the methods of hatchet-welding Carrie Nation are out of fashion, temperance devotees are seeking legal strictures that will limit and decrease alcoholic beverage consumption by all Americians, not just by present and potential alcoholics.

"There are a lot of crosscurrents in this," DeLuca said recently.