By JEFF E. SCHAPIRO

Times-Dispatch Staff Writer

The Virginia Supreme Court dealt a potentially devastating blow today to last year's hard-fought transportation fix.

The state's highest court, in ruling this morning, threw out as unconstitutional the portion of the plan that allows Northern Virginia localities to impose regional taxes for road and rail improvements.

Those taxes -- the Northern Virginia Transportation Authority started collecting them Jan. 1 -- would support bonds, the sale of which could generate millions of dollars to pay for transportation projects in the region.

In a unanimous decision written by Virginia's newest justice -- S. Bernard Goodwyn, an appointee of Gov. Timothy M. Kaine -- the court said it's illegal under the Virginia Constitution for the General Assembly to extend tax powers to an unelected body.

The legislature can provide such power to a county, city, town or regional government. But as the Supreme Court pointed out, the NVTA is none of the above.

This decision -- in it, the high court reverses a ruling by a circuit court judge in Arlington County -- potentially throws the 2007 transportation initiative into chaos. Regional authorities for Northern Virginia and Hampton Roads were a major component of that measure.

The General Assembly, in league with Kaine, is unraveling another of the plan's controversial features: so-called bad-driver fees that were supposed to generate about $65 million a year. The public was enraged by the penalties because they only applied to Virginia motorists -- not out-of-state drivers.

"I am disappointed by the Supreme Court’s finding that the limited authority to impose taxes granted by the General Assembly in 2007, by an overwhelming vote by both bodies, was unconstitutional," Kaine said in a statement today. "I remain committed to working with the General Assembly to ensure that the commonwealth provides adequate funding for our transportation needs."

Patrick McSweeney, one of the lawyers for the Republican legislator who initiated the lawsuit, Del. Robert Marshall of Prince William, describes the decision as "very gratifying."

The ruling could force the legislature into special session to repair the road-and-rail initiative so that it comports with the Supreme Court's guidelines. That could revive the sharply partisan fight over new general taxes -- something Republicans have stoutly resisted.

As McSweeney said, for the General Assembly, "The choice is pretty clear: You either change course on transportation or continue funding in the old ways, which didn't work and shows no prospect of working in the future."

Attorney General Bob McDonnell said, "We intervened in this case as is our obligation to defend challenges to the constitutionality of legislation passed by the General Assembly. The Virginia Supreme Court has spoken, we respect their decision, and we will advise our clients appropriately based on today’s ruling."

Speaker William J. Howell, R-Stafford, said yje decision was disappointing "to those of us who continue to support improving our roads, reducing congestion and increasing mobility for all Virginians. We will be reviewing this decision carefully and remain committed to sorting out the long-term prospects for the regional plans in a timely manner."