He has published widely in the area of psychology and law. Dr. Johnson is also a licensed psychologist with a consulting and clinical practice. He provides examinations and testimony in criminal cases and also cases where the state seeks to terminate parental rights. He has been a member of the New Jersey Association of Black Psychologists since 1986. He is also a member of the Peoples Organization for Progress, the NAACP, the New Jersey Psychological Association, Amnesty International, and other advocacy groups. He has served on the Executive Committee of New Jerseyans for Alternatives to the Death Penalty since 2001. His interests also include: Wrongful Convictions of African-Americans, Family Court Consultations, and Interrogation and Confession.