Gregory B. Craig, a Washington lawyer, was White House counsel from January 2009 to January 2010.

On Aug. 6, 1965, I was working in Coahoma County, Miss., trying to register new voters at the courthouse in Clarksdale. For many weeks, I and other civil rights workers in our project had been knocking on doors, persuading African Americans to go down to the courthouse, stand in line, risk retaliation, take a detailed written test and, inevitably, be rejected as unqualified. We would then ask each rejected applicant to sign an affidavit. We collected those affidavits and sent them in bundles to the Civil Rights Division of the Justice Department. The purpose of this effort was to show that African Americans in the South wanted to vote and that this particular person had been prevented from registering for no reason other than his or her race. That summer, we persuaded 500 African American citizens in Coahoma County to try to register to vote. Four or five passed the test. The rest signed affidavits. We prayed that federal officials would read the affidavits and do something about the situation....

Many months later, I asked one of my Harvard professors — a distinguished legal historian who was also the biographer of Oliver Wendell Holmes — whether there was any concern about the constitutionality of Congress passing a law that imposed requirements on some states when it did not impose the same requirements on other states. He said: “No. We fought a very bloody war about that same question: the proper role of the federal government when it came to protecting the rights of an American citizen. The South lost that war; and in 1870 the country, to make itself absolutely clear on that issue, adopted the 15th Amendment. That amendment put the issue to rest.”...