McLEAN, Va. (AP) – A district judge has ruled that key components of Virginia’s drunken driving laws are unconstitutional, citing a decades-old U.S. Supreme Court decision.

The state law presumes that someone with a blood alcohol content of 0.08 or higher is intoxicated, denying their right to a presumption of innocence, Judge Ian O’Flaherty ruled in dismissing charges against at least two alleged drunken drivers last month.

“I am sure there will be lawyers out in the field making similar arguments tomorrow,” Steven Oberman, chairman of the DUI defense committee at the National Association of Criminal Defense Lawyers, said in a telephone interview Thursday.

Corinne Magee, a defense lawyer who first successfully argued the issue to O’Flaherty, said the ruling is based on a 1985 U.S. Supreme Court case that deals with prosecutors’ obligation to prove all elements of a crime beyond a reasonable doubt.

Magee said Virginia’s law presumes the blood-alcohol level at the time the test is taken is equal to the level at the time of the offense, even if the test occurs hours after police make a stop.

Prosecutors are now taking steps to avoid O’Flaherty on all drunken driving cases, withdrawing cases assigned to him and instead obtaining indictments that send the cases directly to Circuit Court. Prosecutors cannot appeal cases dismissed by a district court judge, but could appeal if a circuit judge makes a similar ruling.

Fairfax County Commonwealth’s Attorney Robert F. Horan Jr. did not return phone calls seeking comment Thursday.

Patrick O’Connor, president of the northern Virginia chapter of Mothers Against Drunk Driving, said the decision “undermines the efforts of the police and prosecutors to enforce the DWI laws, puts drunk drivers back behind the wheel and potentially denies justice to victims of drunk drivers.”

O’Flaherty declined to comment; rulings in District Court are made orally so there is no written ruling outlining his rationale.

Del. David Albo, a defense lawyer, said he sees no difference between a presumption of intoxication at 0.08 and a presumption of speeding at 80 miles per hour.

“So far not a single judge in Virginia has ruled the same way,” he said. “It’s just one judge.”