Alexandria Assistant Commonwealth's Attorney Joseph McCarthy said yesterday he will prosecute 15 men arrested in July on charges of soliciting an undercover policewoman for prostitution under a rarely used city ordinance that defense lawyers are calling "illegal."

On Friday, McCarthy conceded that the state statute under which the men were originally charged appears to cover the prostitutes but not their patrons. Now he plans to prosecute them under a broader 1982 city ordinance that prohibits "soliciting for immoral purposes."

Commonwealth's Attorney John Kloch said he was not aware of any other jurisdiction in Virginia that has tried to prosecute the "purchasers of prostitution." He said, "Usually, the police go after the seller."

Attorney Carl Womack, representing one of the defendants, argues that the city ordinance is "illegal" because "the state never granted the city the power to make such a law."

But Kloch said that while a city law could never override a state law, the state "has given the city the broad police powers to pass stricter ordinances."

Both prosecutors and defense lawyers are scheduled to meet with General District Court Judge Robert T.S. Colby on Nov. 27. At that time, Colby will rule on whether the city law can in fact be applied.

Unlike Virginia, the District and Maryland criminal codes specifically mention "the procurers" of prostitution as misdemeanor offenders, according to Montgomery County and D.C. prosecuting attorneys. However, they say, in both jurisdictions the rule is rarely used. "We will enforce the rule when it becomes a public nuisance," said Montgomery County Assistant State's Attorney Sarah Forden. "But I can't remember the last time I saw a case like this actually come to court."

If convicted of the misdemeanor charge, the 15 men could face up to a year in jail and a $1,000 fine.

Police spokeswoman Lucy Crockett said they are awaiting the outcome of the court ruling before making any more arrests of patrons. "It's a difficult problem to eradicate," Crockett said of the solicitations, which occur mainly along the area known as the "King Street-Rte. 1 Corridor" between Patrick and Henry streets. "The sentencing for prostitutes is fairly light," she said, "and it's difficult to keep the same people from being involved again."

Kloch said the Commonwealth's Attorney's office "has counseled the police to fight the problem both ways, with an undercover purchaser and an undercover seller of prostitution." He said he has not seen a major increase in the problem, but said, "It finds its place where there is least resistance and I don't want that to be Alexandria."