The way Louisiana's Republican leaders put it, the pervasive racial discrimination in elections that led to the passage of the 1965 Voting Rights Act is all in the past. That is why they are now urging the Supreme Court, in a case being argued on Wednesday, to bar states from using any consideration of race when drawing legislative districts, gutting a key plank of the law that was designed to ensure Black voters would have a chance of electing their preferred candidates.