As soon as President Lyndon B. Johnson introduced a voting rights bill to Congress in mid-March 1965, the Civil Rights Division began working out the details of exactly what it would need to do to make the law work. This was, to be sure, a difficult task, as they didn't yet know what the final text of the law would be and didn't know when exactly it would be passed. But they were determined to hit the ground running.
There was, um, a lot to do.
From the start, the voting rights bill called for the use of federal "examiners" who could be sent by the attorney general into specific counties where the regular registrars had refused to enroll African Americans – but who would those examiners be, where would they come from, how would they be trained? The Civil Rights Division worked for months with the heads of the Civil Service Commission, finding native southerners from various federal agencies – retired postmen and IRS agents, for instance – and holding a training session for them in D.C.
The decisions about where these examiners would be sent would be made by the attorney general, who would of course be relying entirely on the arguments made in "justification memos" drafted by Division lawyers. But because the VRA required demographic data for those memos, the lawyers also spent a good deal of time working out arrangements with the U.S. Census Bureau. Because of their coordination ahead of time, a process mandated by the law – in which the attorney general would send requests to the Bureau, and the Bureau would take its time doing its necessary research, and then the Bureau would mail that back to Justice – could be done in minutes. They'd be able to send examiners anywhere they wanted almost immediately.
That said, the government hoped to use these federal examiners sparingly, believing that voluntary compliance was the only path to lasting democratic reforms.
And so as some of the CRD lawyers raced to train federal examiners, others spent this time touring the South talking to the existing local registrars and convincing them it would be much better if they simply did their job instead of forcing the feds to do it for them. The CRD drafted letters that the attorney general sent to 529 county registrars across the South, spelling out in great detail their responsibilities and a warning for what would happen if they failed.