IT IS generally acknowledged that discrimination by D.C. cabdrivers comes in two flavors. Blacks, especially at night, too often find that hackers ignore their efforts to obtain a ride. Cabbies also refuse service, regardless of the color of the riders, when the destination is Southeast Washington. Which drivers practice such discrimination? If you assume that most are white, you're in for a surprise.

Last year, the Washington Lawyers Committee, Howard University and the law firm of Hogan and Hartson conducted a study of cabdriver bias in the District, using a variation of the court-approved method called "testing," in which similarly dressed whites and blacks were sent out to hail cabs. In 292 tests, blacks were seven times more likely to be refused service.

A related federal court lawsuit, filed against three city cab companies on behalf of the Southeast Vicariate Cluster church group, named eight drivers: Endale Eteffa, Haq N. Malik, Safdar Hussain, James Jones, Frew Tibubu, James Williams, Albert Williams and Sium Ghurmai. All were either black Americans, Middle Easterners or Africans.

But such discrimination is unacceptable, regardless of who practices it. Also, cabdrivers who refuse Southeast fares often claim that the area is too dangerous. But when all serious crimes against persons are considered, Wards 7 and 8 do not compare unfavorably with other parts of the city. In fact, a 1988 D.C. police study of some 500 homicides showed that the two census tracts in the city where the most murders occurred were located in Ward 1, in Northwest Washington.

Fortunately, this week's court settlement provides a means to combat the problem. Among other things, the three cab companies -- Empire, D.C. National and American -- must now police the conduct of their drivers and investigate and keep a public record of all complaints. When service has been denied on the basis of race, the driver's insurance and license will be suspended for a week on the first offense, for 12 days on the second offense and a third offense results in permanent suspension.

The three companies have also agreed to petition the D.C. Taxicab Commission to require all Washington cab companies to do the same. Perhaps now, blacks and those who are trying to travel into Southeast will find hailing a cab a less discouraging experience.