Eight demonstrators against abortion were acquitted of trespassing charges yesterday in Fairfax General District Court when Judge J. Mason Grove ruled Virginia's abortion statute unconstitutional.

The prosecutor, Steven Merril, said the ruling sets no precedent and in effect is valid only for yesterday's case.

While the ruling is not binding on other judges in the 19th Judicial District, which includes Fairfax and Prince William counties, Fairfax City and Falls Church, the judges in the district would as a practical matter probably go along, according to Robert M. Hurst, chief judge of the district.

Yesterday's trial stemmed from incidents Nov. 12 and Jan. 6 at the Northern Virginia Womens Medical Center at 3918 Prosperity Ave.

Aside from freeing the defendants, Deputy Commonwealth's Attorney Merril said, the main effect of yesterdays ruling is that "it really leaves that abortion clinic in a very difficult position as far as receiving some relief from the court in trespass cases."

In a trial Oct. 17 before Judge Lewis H. Griffith of the General District Court, six persons were acquitted of trespassing charges in connection with a May 14 demonstration at the same clinic.

In the cases, Judge Grifflth ruled that the protesters were following their belief that their action was justified to save lives.

Merril said he argued yesterday the Judge Griffith's ruling should not apply, contending that the law should enable outsiders to intervene only to prevent an accidental or unlawful act.

The abortions in question were neither, he asserted, since the Virginia statute permits physicians to perform abortions through at least the first trimester (three months) of pregnancy.

Only by ruling the law unconstitiutional could the judge acquit the defendants, Merril argued.

After yesterday's ruling, Merril suggested that the clinic might seek relief by bringing a civil action in the Circuit Court. A ruling there that the law was constitutional would be binding on the District Court, he said.