The Maryland Court of Appeals, the state's highest court, ruled yesterday that a referendum question that sought to force Montgomery County to give up its monopoly over liquor sales cannot appear on the November election ballot.

The court said the referendum, sponsored by Del. Robin Ficker, was invalid because the state law that allows such a monopoly can be repealed only by another state law.

The court's ruling, which removes one of this election year's most politically explosive issues, came just hours after County Executive Charles W. Gilchrist held a press conference in front of one of the county's 20 liquor stores to announce a new crackdown on store owners who violate county liquor laws.

Gilchrist said he will spend $50,000 in additional overtime for police officers and county liquor inspectors to step up surveillance of all alcohol sales. He also announced that $60,000 of the county's profits from its liquor monopoly will go into a new advertising campaign to warn people about the dangers of alcoholism and drunk driving.

The crackdown is supposed to add about 400 evening visits each year to liquor outlets around the county. The county has 20 liquor stores, and there are 512 outlets licensed to sell liquor in the county.

Gilchrist said the new measures were initially recommended by a liquor task force, which concluded that the county should stay in the liquor business but exercise more control over drinking and increase public awareness about alcohol. Gilchrist, who is running for reelection, denied that the press conference had political overtones, despite the Ficker referendum and the current election-year debate over whether the county should remain in the business of marketing liquor.

Gilchrist said he was not trying to use the occasion -- a press conference in front of television cameras flanked by posters on the evils of drunk driving -- to tout the advantages of having the county in the liquor business, although from a public relations standpoint, the timing could not have been better.

Joseph C. McGrath, Gilchrist's Republican opponent and a staunch believer in free enterprise economics, wants the county to end its liquor monopoly. At a press conference yesterday, McGrath said, "I feel the county should be out of the business of the sale and distribution of liquor."

Those in charge of enforcement welcomed the new attention to their efforts.

A.P. Cassidy, chairman of the Board of License Commissioners, said that since January, 37 merchants have been cited for violating some liquor law. Most violators either receive a fine or have their license temporarily suspended.