A federal judge yesterday gave Metro two months to agree to build a controversial subway line to Vienna, or face the possibility of having to return the $2 million Fairfax City has paid for the Metro system since 1970, plus interest.

Judge Oren R. Lewis in Alexandria ruled that Metro broke its 1970 agreement when it excluded Fairfax City from voting on the stopgap Metro financing plan, which excluded 40 miles of the projected 100-mile subway system, including the Vienna route. The agreement was drafted because Metro does not currently have enough funds to complete the entire system.

Metro officials said Fairfax City was excluded from voting because it had already completed its financial obligations to the system.

Although Judge Lewis said Metro had broken its 1970 agreement, he lifted his temporary injunction blocking the subway agency's implementation of the stopgap plan.

Metro and the Washington-area governments that are members of it, can appeal Lewis' decision to the Fourth Circuit Court of Appeals, refuse to complete the subway to Vienna and face court hearings on damage payments to Fairfax City, or agree to build the subway line and devise a method to finance it.

Both Metro and Fairfax City officials said they considered the judge's 15 page decision a partial victory.

"We're at least relieved that we have the option to keep construction going," said Theodore Lutz Metro's general manager. "We had hoped we would get completely cleared."

"We're very happy of course," said Fairfax City Mayor Nathaniel Young. "We felt we had a good case and the judge has vindicated our judgment.We've been criticized considerably for believing such things. I think he (Lewis) threw it to them."

The jurisdictions and the Metro board will meet within the next two weeks to decide what action to take, Lutz said. He said it was too soon to predict whether other jurisdictions whose Metro lines were excluded from the 60-mile plan also could seek return of the payments they have made to Metro.

"Eventually we're apt to have a total revision of the plan," Lutz said, referring to the future of the jurisdictions' obligations to Metro. "We either hammer it out together or hammer it out in court."

"All the legal beagles have to get their heads together to decide whether to appeal this thing," said Fairfax County Board Chairman John F. Herrity. "It is significant though that Judge Lewis is probably the most reversed judge over there."

The haggling and bitter disagreements among the eight Metro jurisdictions did not begin with the Fairfax City lawsuit over the Vienna line. Fairfax City last year eliminated any possibility for Northern Virginia jurisdictions to finance part of their Metro contributions through a 4 per cent gasoline sales. Fairfax City was the only locality to oppose it, thus preventing four other jurisdictions from imposing it even though they approved the levy.

The most recent dispute over the interim financing agreement began when a series of regional meetings was held to devise ways to finance Metro construction with the money now available. Fairfax City, which had contributed $2 million since 1970 as its full share of building the Metro line to Vienna in the Interstate Rte. 66 median, did not attend.

Representatives from the other seven jurisdictions developed a plan to finance construction of all the Metro mileage that had no planning or political barriers.

The local governments would contribute $125.8 million under the stopgap plan. Metro would provide $59 million from interest on its investments. The U.S. Department of Transportation would be asked to provide about $758 million.

With this funding the Huntington route to Fairfax County and the Shady Grove route to Montgomery County and portions of four other routes in Maryland and Virginia, including the Vienna route as far west as Glebe Road in Arlington could be built, Metro has said.

When Fairfax City refused to consent to the agreement, Metro "and the remaining defendant political subdivisions proceeded to approve and agree to sign the interim agreement without the city," Judge Lewis wrote in his opinion.

". . . By so doing, they have subjected themselves to the penalties flowing from the breaches of the agreement," Lewis said.

"All of the jurisdictions, with the exception of the City of Fairfax - and possibly Fairfax County - will have gotten practically all of the routes originally scheduled for their jurisdictions brought to operational status under the interim agreement," Lewis said.

"The City of Fairfax is the only jurisdiction that has paid all of its share of capital contributions - and it is in danger of getting very little for its money if the (Vienna) route" is not completed as originally planned, Lewis said.

Lewis also ruled that Metro broke its 1970 contract by not recomputing how much each jurisdiction must pay in order to finance the $5 billion system. The recomputations were supposed to be made in 1974 and 1976 and every two years after that, Lewis said.

Lewis said the recomputations of the cost to build Metro are necessary to "invoke the best efforts" of the jurisdictions in meeting their contributions to the system.

Metro officials said the interim agreement was planned only to provide funds for construction before the jurisdictions' "best effort" pledges could be paid.

But Lewis said the interim agreement was designed to "bring to revenue operation" one those routes explicitly listed in the 60-mile plan.

"The agreement funds the completion of some of the routes at the expense of the remainder," and therefore breaches the 1970 agreement, Judge Lewis ruled.