i think you might have a case if we were referring to a lower tier in the justice system, i.e. stop & searches by police on the streets. at the level of prison convictions, "people like me" probably isn't sufficient enough an explanation to explain the distortion between the distributions by such a high factor.
i think something horrendous like 40% of black individuals are on the national dna database. your thoughts are probably correct with respect to that.