IN APPOINTING a capable and knowledgeable black man to be a deputy police chief, Prince George's County Executive Lawrence J. Hogan has taken an important step on behalf of law enforcement authorities as well as the citizen they are charged with protecting. As Mr. Hogan has said consistently since taking office, there has been and still is a "vital need for minority representation in the upper ranks of the police department." Members of the force should recognize the appointment as a responsible move to stengthen the department as a cohesive unit that can command new respect throughout the county.

The appointee, Thomas M. Davis, brings solid experience and special talents to the job. Not only has he worked as a civilian employee of the police department for six years, but also Mr. Davis has taught at the County Police Academy and has developed special classes for recruits. In his new position, which he takes up July 1, Mr. Davis will be in charge of personnel -- and that , he says, will include directing recruiting campaigns beyond the immediate area.

The recruiting effort is a significant complement to the useful changes that have been under way for some time now in the Prince George' police department. Six years ago, the 825-member force was less than 5 percent black; today, there are 850 members on a force that is 12 percent black -- but no black has rank above sergeant. This is in a county that is 36 percent black. It is not a matter of making statistics balance out exactly; efforts to close the gap cannot help producing a more effective force.

Voters in the county clearly recognized the importance of accelerating this process when they approved a referendum last year that was proposed by the county council. The vote authorized the creation of three deputy chiefs who could be outside the county merit system and therefore would not have to rise through the ranks. This week, County Executive Hogan has followed through: "Even though I am convinced we do not have a problem of racism or brutality in the department, this is the culmination of an effort in trying to address the problem, real or imagined." With further understanding and acceptance, it can work to ensure that the problem is neither real nor imagined -- just eliminated.