More than two years after a judge ruled that Mississippi's method of electing judges violated the federal Voting Rights Act, eight black judicial candidates are on the ballot in elections today. Also on the ballot are three proposed constitutional amendments. One would eliminate the long unenforced poll tax law. In April, 1987, U.S. District Judge William H. Barbour Jr. of Jackson, Miss., ruled that the state's judicial districts discriminated against blacks and ordered some districts redrawn. The ruling was upheld by the U.S. 5th Circuit Court of Appeals.