“The Voting Rights Act remains a necessary vehicle to protect the most fundamental right we have in this democracy,” said Rep. Mel Watt, D-N.C., who helped rewrite the law in 2006.

Lawmakers in 1965 originally described preclearance as a temporary measure, saying in the official 1965 House of Representatives report that they expected that preclearance “would no longer be needed” by 1970. Nonetheless, preclearance has been extended in five consecutive rewrites of the law. The 2006 rewrite extends it for an additional 25 years.

“Congress saw substantial evidence of continuing discrimination,” NAACP Legal Defense and Education Fund attorney Debo Adegbile said Friday. “The remedy is clearly necessary. . . . It’s strong medicine for a strong problem.”

Supporters of the law further stress that covered jurisdictions can bail out – avoid its demands – if they can show there was no voting discrimination in the prior 10 years. One hundred and ninety jurisdictions have bailed out so far.

Everyone agrees there’s been progress. In 1965, fewer than 20 percent of eligible African-American residents of Alabama were registered to vote. There were no African-Americans in the state legislature. Now, voting registration has skyrocketed and African-American members account for about a quarter of the state legislature.

“Nothing in the record suggests that covered jurisdictions remain engaged in the pervasive voting discrimination and electoral gamesmanship that once made case-by-base adjudication of constitutional violations a futile enterprise and spurred Congress to act,” Shelby County’s attorney, Bert Rein, wrote in a brief. “Current conditions cannot justify preclearance.”

The Shelby County challenge is following a 2009 challenge raised by a small Austin, Texas-area utilities district. Though the court in 2009 left the Voting Rights Act intact, Chief Justice John Roberts Jr., in words that now read like a foreshadowing, warned that preclearance’s days might be numbered.

“The statute’s coverage formula is based on data that is now more than 35 years old,” Roberts wrote, “and there is considerable evidence that it fails to account for current political conditions.”