Bernice Just, a member of the D.C. Law Revision Commission and former director of the Washington Pretrial Justice Program, has announced her candidacy for the Ward 5 seat on the D.C. City Council.

With her announcement, Just became the third person to challenge incumbent William R. Spaulding in the Sept. 12 Democratic primary. Robert Artisst and Roland Rier have already announced their candidacies.

Just said her legislative priorities include the protection and stabilization of neighborhoods so current residents can continue to live there, the stimulation of small-business development and improvement of retail shopping facilities and encouraging the participation of youths in the legislative process.

She said she favors "a fair and equitable" tax on the incomes of commuters who work in the city and live in the suburbs.

Just, 57, a resident of Washington since 1936 and a lawyer, lives in the Brookland area and is a member of the Brookland Civic Association.

A graduate of Dunbar High School and Howard University, she has served on many professional and civic organizations, including several affiliated with the D. C. Bar.

She was employed for 12 years as budget and program analyst for the predecessor of the U.S. Department of HOusing and Urban Development. In 1969, she organized the Washington Pretrial Justice Program under auspices of the American Friends Service Committee and served as its director until recently. The program monitored and documented problems of the criminal justice process in Washington.

In 1975, she was appointed by the City Council to the Law Revision Commission, which is drafting legislation to modernize the city legal code.