The VRA is far more than Section 5, and it is and always was more flexible than the majority suggested. For one thing, "covered jurisdictions" have always had the opportunity to get out from under the preclearance requirement. Under Section 4 of the VRA, they could go to court and demonstrate that they have "stop[ped] discriminating on the basis of race" for a period of ten years. As Justice Ginsburg pointed out in her dissent in Shelby County, 200 jurisdictions have successfully "bailed out" of preclearance--with no objection from the federal government.
Shelby County never sought to bail out. It couldn't show that it had "stopped discriminating on the basis of race," because, well, it hadn't. Among other questionable acts during the previous decade, the county had actually defied the Act, holding a election under a new law for which it did not seek preclearance. Justice Sonia Sotomayor pointed out during oral argument that Shelby County "is the epitome of what caused the passage of this law to begin with," and the county didn't bother to deny it. Rather than expressing remorse for its racist past, it came before the Court more like a sulky teenager complaining he'd been grounded just for stealing the family car a few times: Why am I grounded when other kids aren't? Can't we just forget the whole thing? For all the sternness of its anti-racist language ("any racial discrimination in voting is too much"), the majority handed Junior back the keys without so much as a "you be good now."
What Holder has done will be spun as a "challenge" to the Court. Congressman Lamar Smith of Texas has already produced a statement saying, "the Supreme Court message to the Justice Department was clear - don't mess with Texas. But Eric Holder and the Justice Department aren't listening." Legally, that's nonsense. The Court explicitly said that jurisdictions could be singled out "on a basis that makes sense in light of current conditions." The DOJ suit makes exactly that claim--current conditions in Texas violate the Constitution.
What is the "opt-in" provision? Although Section 5, the preclearance section, has attracted most attention recently, Section 3 of the Act (codified in 42 U.S.C. § 1973a) permits both the Justice Department and private plaintiffs to challenge election practices in any state or locality. In such a case, the plaintiffs may be able to prove that the practices they are challenging violate not just the Act, but the Constitution itself--either the Fourteenth Amendment's guarantee of equal protection or the Fifteenth Amendment's bar on racial discrimination in voting. If the government or the plaintiffs do prove a constitutional violation, Section 3 says, "the court . . . shall retain jurisdiction for such time as it may deem appropriate"--and while it does, the state or local defendants are barred from making changes in voting without approval either of the court or of the Justice Department.