Outlaw single-member districts
Guy-Uriel Charles has a column in Findlaw's Writ entitled, Should Single-Member Districting Be Held Unconstitutional? He argues that single-member districts allow for gerrymandering and that cumulative voting would undercut gerrymandering.
Our society is too heterogeneous and we have too many cross-cutting political identities to tolerate political gerrymandering in its present form. Yet politicians will never, on their own, be able to resist the temptation to manipulate the lines for their own benefits -- any more than they could restrain themselves from creating districts that violated the one person-one vote principle before Baker v. Carr.