The Rooker-Feldman doctrine states that: a losing party in state court is barred from seeking what in substance would be appellate review of the state judgment in a United States District Court, based on the losing party's claim that the state judgment itself violates the loser's federal rights.

"If the lesson of tingles is that society's racial and ethnic cleavages sometimes necessitate majority-minority districts to ensure equal political and electoral opportunity, that should not obscure the fact that there are communities in which minority citizens are able to form coalitions with voters from other racial and ethnic groups, having no need to be a majority within a …

—"[w] hen applied to a claim that single-member districts dilute minority votes, the first Gingles condition requires the possibility of creating more than the existing number of reasonably compact districts with a sufficiently large minority population to elect candidates of its choice."

—affirming, upon a finding of no vote dilution, District Court decision not to give § 2 remedies to both African-Americans and Hispanics because population overlap made the remedies mutually exclusive

—holding that because the United States was not a party to the state court action, Rooker-Feldman was not a bar to its federal claims

The court failed to ask whether the totality of facts, including those pointing to proportionality, showed that the new scheme would deny minority voters equal political opportunity

The concept of proportionality in a Section 2 case "links the number of majority-minority voting districts to minority members' share of the relevant population

"[P] roportionality... is obviously an indication that minority voters have an equal opportunity, in spite of racial polarization to participate in the political process and to elect representatives of their choice

[CITATION] League of United Latin American Citizens v. Perry