IN NOMINATING Charles F.C. Ruff to be U.S. attorney for the District of Columbia, President Carter has chosen an exceptionally qualified person for a most important job. In addition to performing the customary duties of a federal prosecutor, the U.S. attorney for this city prosecutes local criminal cases such as murder and burgulary. Mr. Ruff seeks a significant and welcome change in this arrangement. He already has demonstrated his keen interest in District affairs through his sensitive assistance in moving the District to the next stage of self-government: full control over its local criminal justice system.

Together with Mayor Barry's administration, Mr. Ruff has worked out a plan with the Justice Department that would strip the local functions from the U.S. attorney's office and transfer them to a local attorney general. The District would assume full control over local criminal justice by 1981. Besides working for congressional approval of this plan, the challenge will be to make the switch without adversely affecting the quality of justice that the city has experienced under the federal arrangement.

For this task -- as well for any other duties connected with the office -- the city is fortunate to have a nominee with such vast legal experience. Mr. Ruff, currently the second-ranking lawyer in the Justice Department, also has been a deputy inspector general in the Department of Health, Education and Welfare, a Watergate special prosecutor and a university professor. As Mayor Barry notes, Mr. Ruff also "comes to the job with a well-earned reputation of fairness and concern for the problems of the city." Other local leaders from all parts of the city have voiced confidence in Mr. Ruff's sensitivity to the concerns of minorities.

So the Senate shouldn't take a lot of time to confirm Mr. Ruff. He is ready to help the District take away authority from the office to which he has been nominated. This commitment, if pursued with the same fairness and diligence Mr. Ruff has demonstrated in other posts, would be enormously beneficial to this city.