The Virginia Supreme Court, in a ruling that angered anti-drunken driving groups, yesterday ordered a new trial for a Fauquier County man convicted of second-degree murder in a 1981 automobile accident that killed three persons.

Some prosecutors said the decision will make it extremely difficult to prosecute anyone in Virginia for murder in a drunken driving case, a tactic used increasingly in an effort to cutail drunken driving.

Anti-drunken driving activists and Fauquier County prosecutors expressed anger at the ruling, which overturned the conviction of Warren Wesley Essex, 27, a construction worker who served 15 months of a five-year sentence stemming from the Nov. 20, 1981, collision.

The court said that prosecutors may have had the facts to prove Essex guilty of manslaughter, the more frequently used charge in drunken driving cases resulting in death, but that they did not prove the defendant was malicious -- an element necessary to convict someone of second-degree murder in Virginia.

The court said that the prosecution failed to prove that Essex "embarked upon his ill-fated course of conduct willfully and with a malicious purpose."

"I'm appalled, I'm incensed, I feel like I've been kicked in the stomach," said Roger Inger, the assistant Fauquier County commonwealth's attorney who prosecuted Essex for a year and a half. "I completely disagree with the court's analysis."

"What do you call this if not murder?" said Ed Kunec, a Northern Virginia anti-drunken driving activist. "We're overrun with too many lawyers in this country."

Inger said his office probably will not bring Essex to trial on the manslaughter charge because he has served more time in jail than he likely would receive if convicted. Manslaughter is punishable in Virginia by one to five years' imprisonment.

The case against Essex was the first second-degree murder case in Virginia stemming from a drunken driving incident. Since his conviction, the same charges have been brought against at least 10 persons in Virginia in similar cases, and most of them have pleaded guilty, Inger said.

"A person who gets drunk and gets behind the wheel of a motor vehicle is committing a willful act," Inger said. "He didn't intend to kill anybody, but that doesn't change the character of his act."

Fairfax Commonwealth's Attorney Robert F. Horan Jr. said he is not surprised by the court's ruling. "You can't have murder unless you can show a killing is intended," Horan said. "I always thought that's the way the Supreme Court would come down on this."

The court's ruling yesterday reached an opposite conclusion from a ruling by the U.S. 4th Circuit Court of Appeals in Richmond three months ago upholding the second-degree murder conviction of David Earl Fleming, 57, in the death of Margaret J. Haley, 55, of Fairfax County.

Haley, a mother of 11, was killed June 15, 1983, when a car driven by Fleming struck hers head-on on the George Washington Memorial Parkway.