A federal judge in Alexandria has declared that Arlington's regulations on student publications are "unconstitutionally vague" and also temporarily restrained the county school system from further disciplining a student who distributed an undergound newspaper.

Judge Robert R. Merhige Jr. said Arlington's regulation requiring that student publications conform to the "journalistic standards of accuracy, taste and decency maintained by the newspapers of general circulation in Arlington" is "a monument to vagueness."

Merhige made his finding in a suit brought by Joshua Leibner, 17, a Washington-Lee High School junior who was suspended last Nov. 5 for 10 days when he distributed a one-page fictional and satirical newspaper after the school's principal, William Sharbaugh, forbade it.

Under a temporary restraining order issued by Merhige, Washington-Lee officials cannot punish Leibner for distributing the paper on school grounds for the next 10 days. Merhige said that period of time would give Leibner's American Civil Liberties Union attorney an opportunity to seek a temporary injunction prohibiting any further disciplinary action against Leibner. The youth said he would distribute another copy of the paper, called "The Green Orange," on Wednesday.

"The issuing of a restraining order, although an interference with school policy, will not unduly burden school officials," Merhige said in his opinion, which was signed Friday and made public yesterday.

"Any burdens which do arise are necessary because we cannot permit those conditions to supress the First Amendment rights of individual students. The court's observation in this regard indicates that the public interest indeed is advanced by the protection and not repression of First Amendment activity," Merhige said.

School officials declined comment on the case until it is completed.

Merhige's decision is the second ruling within the last week favoring First Amendment rights for high school students. U. S. District Court Judge Albert V. Bryan Jr. alst Thursday ruled Fairfax County school authorities could not prevent two Hayfield High School students from printing a story in the official school newspaper about birth control. Bryan said high school newspapers were covered under free press guidelines of the First Amendment.

Leibner first published his newspaper on Oct. 17, after receiving a warning from Sharbaugh not to print it. Leibner, the writer, publisher and editor of The Green Orange, distributed another issue Nov. 5 at a football game after a second warning from the principal. He was then suspended until Nov. 15.

In a letter to Leibner's parents, Sharbaugh said The Green Orange was distributed without receiving prior approval from him, Leibner did not have his name printed on the issue and the paper was of "questionable taste, decency and journalistic standards." The principal said all of these points violated school regulations.

Affidavits from the principal and two students said the paper "might offend certain segments of the student population - particularly racial minorities - and lead to acts of physical confrontation."

"I think the administration took the paper literally," Leibner said yesterday. "It's an obvious peice of Lampoonic humor."

An example of Leibner's work is an article in one of the issues about a fictitious Washington-Lee student who was asking to be executed:

"In one of the most dramatic confrontations in the over 50-year history of Washington-Lee high school, senior Tom Cannon stood before the school's principal and members of the school board and requested of them that they allow him to be executed rather than serve out 96 detentions he had accumulated."

Leibner filed suit Feb. 18 asking for a temporary restraining order against school officials on grounds that the rules prohibiting him from distributing his paper on the school campus were unconstitutional.

The rules state, in part, that students must submit a copy of a paper's text to the school principal at least one school day before distribution.

Another part states that the publication must conform to journalistic standards of accuracy, taste and decency maintained by the newspapers of general circulation in Arlington."

"This 'standard' represents a monument to vagueness," Merhige said. "There are no guidelines or criteria by which such levels of accuracy, taste and decency may be ascertained by either the author of literature or the reviewing principal."

The regulations also prohibit obscenity.

"Proscriptions against distributing obscene or libelous material do not define those terms," Merhige ruled. "This too renders the regulation unconstitutionally vague."