The following pages in this Voting Rights section mostly involves the federal Voting Rights Act of 1965, but as Section 2 was amended in 1982. Thornburg v Gingles is first, a lay person's policy - not legal - take on the 1986 US Supreme Court case that still serves as a flawed precedent for any vote dilution claims made under Section 2 of the federal Act. The amendments were critical in allowing claims based on the discriminatory effects of a voting scheme, not its intent.
Next, you'll find a variety of resources on the use of "modified at-large" remedies such as Cumulative Voting, and then Single Transferable Vote, as alternatives to the default Gingles presumption of single-member districts. You'll also find material related to litigation filed under states Voting Rights Acts, of which there are currently just two: California and Washington.
Additional material located on these Voting Rights pages: