Lawyers for Fairfax County asked U.S. District Court Judge Oren R. Lewis yesterday to stop the Justice Department from cutting off $450,000 in federal aid pending the outcome of a federal discrimination suit against the county.

The Justice Department, arguing against the county, cited comments in a Jan. 4 television interview by John F. Herrity, chairman of the County Board of Supervisors, that the federal aid is ineffective. Lewis indicated the would rule on the county's request sometime next week.

The funds, which are administered by the Law Enforcement Assistance Administration, support programs that involve the treatment of alcoholics, mental health care, child abuse, juvenile detention and the training of court personnel.

Under federal law, Justice can cut off the LEAA aid to a local government body involved in a civil rights suit, 45 days after the suit is filed, although the local jurisdiction can apply to have the funds restored if it wins the suit.

The federal government filed suit in District Court in Alexandria Dec. 19, charging Fairfax County with a pattern of discrimination against women and minority groups in its hiring and promotion policies. The Board of Supervisors voted unanimously to contest the charges.

The county argued yesterday that the suit will probably be long, and that an interruption in the LEAA funds would cripple the programs covered by the grants. But the Department of Justice, arguing that the funds are not as crucial to the county as its lawyers say, cited Herrity's comments in a television interview that the LEAA grants have been "under fire from numerous sources for their lack of, shall we say, effectiveness, anyway. So I don't think we're particularly concerned about that."

The county also says that the government's charge is too vague and cites no examples of discrimination. If the Justice Department wins the suit, it can seek to end the annual $6.5 million federal revenue sharing payment to Fairfax County. Lewis indicated that the trial would begin in April.