D.C. Mayor Anthony A. Williams plans to sign emergency legislation to relax the city's "zero tolerance" drunken driving law, which permits drivers to be prosecuted for blood alcohol levels well below the legal limit.

Williams (D) had criticized the emergency bill as a "hastily written" reaction to public complaints from a small number of drivers. But yesterday, Williams said he would sign the bill because he is "making progress" in negotiations with D.C. Council members over the shape of permanent legislation.

"I'm not completely enthusiastic about it. But I sign a lot of things that I'm not completely enthusiastic about," Williams told reporters at his weekly news conference.

The bill's sponsor, council member Carol Schwartz (R-At Large), welcomed the mayor's support. But Schwartz said she and the mayor remain far apart on the question of when drivers should be presumed to be intoxicated.

"I've said I don't intend to go where they want to go," Schwartz said. "But in an effort to arrive at consensus, I am certainly open to continued discussion."

At issue is a D.C. law that presumes drivers to be under the influence when their blood alcohol content is as low as .03 percent, far lower than the levels in Maryland and Virginia. All three jurisdictions allow the arrest of any driver whom a police officer judges to be impaired, regardless of blood alcohol level. But only the District presumes impairment well below .08 percent, the level at which a driver is legally intoxicated in all three jurisdictions.

After The Washington Post published articles about arrests of drivers with low blood alcohol levels -- including a 45-year-old Virginia woman who said she spent several hours in jail after drinking a single glass of wine -- the council voted last month to amend the D.C. law to make it more closely resemble Virginia's.

The emergency legislation will take effect immediately after the mayor signs it, and a spokesman said Williams plans to do so today. Under the measure, drivers with a blood alcohol level of less than .05 percent would be presumed sober and could not be arrested for drunken driving. Drivers with levels of .05 percent to .079 percent would fall into a "neutral zone" that would require police to use other factors, such as performance on field sobriety tests, to establish impairment and make an arrest.

Williams is opposed to the neutral zone and has argued that drivers who test between .05 percent and .08 percent should still be presumed to be under the influence.

"Impairment for most persons becomes significant beginning at . . . 0.05 percent," Williams wrote in a letter to Schwartz and other council members. "If an individual drinks enough to fall into this range, it is entirely sound public policy to put the burden on the driver to demonstrate that he or she is not impaired."

Schwartz argues that Williams would effectively lower the legal limit to .05 percent.

"I am not going to turn us into the only jurisdiction in the country that says you're presumed to be intoxicated above .05 percent," Schwartz said. "There may be some compromise that can be reached, but I am not going to make our huge hospitality industry operate in an inhospitable place."

Williams says progress is being made on permanent DUI legislation.