Armand Derfner and Gerry Hebert have written this guest post (available as a pdf [CORRECTED FILE]) for ELB, which begins:

Much of the debate in the pending Shelby County case centers on whether the remedy in Section 5 of the Voting Rights Act is “congruent and proportional” to the evidence of violations, as the Supreme Court first began requiring in 1997 in City of Boerne v. Flores. However, simply reading City of Boerne and the cases following it suggests that this is not the right test for evaluating the constitutionality of Section 5, and that applying it would be wholly without precedent.
That may surprise some people who believe – mistakenly – that the Supreme Court has already held that Section 5 must meet a test of “congruence and proportionality.” One such surprised person would be Chief Justice Roberts, who thought (Tr. Oral Arg. 56) the Court applied that test in the 2009 case of N.W. Austin MUD v. Holder. One party in that case did say that test should be applied, but the Court specifically said it wouldn’t address the issue and decided the case on other grounds