Interpret what did chief justice roberts mean when he stated that the voting rights act "employed extraordinary measures to address an extraordinary problem"?

Chief Justice John Roberts meant that the problem of voter suppression had been an extraordinary problem in some states at the time of the Voting Rights Act of 1965 and subsequent decades ... and that because the problem was acute in some states, extraordinary measures had been needed in those states to ensure that all voters' rights were respected.

The statement from Roberts was made in his opening remarks in writing the Supreme Court majority opinion in the case Shelby County v. Holder (2013).  That case challenged the constitutionality of some of the provisions of the Voting Rights Act of 1965.  The majority, by a 5-4 vote, ruled that section 4(b) of the 1965 law is, at least in the present, unconstitutional, because it was relying on 40-year-old data in making its application of extraordinary rules for some states which previously had practiced voter discrimination.  The Supreme Court ruling determined that the law was no longer responsive to current needs and would need to be updated.