Fairfax County last year showed a "marked increase" in removing habitual driving offenders from the highways, according to Mothers Against Drunk Driving, a group that has been sharply critical of the county courts.

Judges in the county last year stripped 46 drivers of their licenses on the grounds that they were habitual offenders, up from nine the previous year, the group said in a new report.

"We now are approaching the state average," said Lou Herzog, president of the Northern Virginia chapter of MADD, who credited pressure his group has brought on Fairfax Commonwealth's Attorney Robert F. Horan Jr. for the improvement.

Horan was not available for comment, but his deputy, V. Britt Richardson Jr., agreed that the office and others have given the issue "more attention."

Under Virginia law, a habitual offender is defined as someone who has been convicted of three or more of the following offenses: voluntary or involuntary manslaughter involving a motor vehicle, drunken driving, driving on a revoked or suspended license and hit-and-run, or someone with 12 or more convictions of offenses involving a motor vehicle.

If a judge declares such an individual a habitual offender in a civil proceeding, his or her driving license can be revoked for 10 years. Any driving offense during that period, such as driving without a license, can result in a mandatory jail sentence.

The Virginia Division of Motor Vehicles, which monitors driving convictions, is charged with notifying local prosecutors of the third convictions. Last year it notified Fairfax officials of 362 such drivers, compared with 309 in the county that it cited the previous year.

Richardson said the relatively low number of habitual offenders in Fairfax is a reflection of the transient nature of Northern Virginia.

"These persons are hard to locate," he said. "They give bad addresses. We live in an urban area with multiple jurisdictions."

William J. Minor Jr., one of the assistant prosecutors in charge of the cases, said that last year his office tried to track down about 100 from DMV's list and only 46 were taken to court. This year, he said, there have been about 150 attempts and at least half have been located, he said.

Richardson cited the creation of a regional network, in which area jurisdictions share information about driving convictions, and the formation of a "master list" of habitual offenders as helping the Fairfax effort. The list is posted at the county jail, and deputy sheriffs are now notified more promptly when an offender is spotted in court on another charge, he said.

The rate in locating habitual offenders has improved because they have been made a priority in the sheriff's deparment, said Fairfax Chief Deputy Sheriff Carl Peed.

"We're chasing them down," said Peed. In the past, he said, if they were not living at the listed address, they were declared "not found."

MADD's court monitoring report showed that last year 25 declared habitual offenders were picked up for driving on suspended licenses. Of those, two cases were not prosecuted, two were dismissed, one person was found not guilty, two had their licenses revoked or suspended and 14 received jail terms of up to three years -- one for two weeks.

While acknowledging improvement in the number of habitual offenders adjudicated and the number of drivers apprehended for driving on suspended licenses, the report concluded that the problem of habitual offenders is just beginning to be addressed in Virginia.