That "pre-clearance" requirement was put into the 1965 law to ensure that redistricting or other changes to voting practice do not act as a hurdle to minority voting rights. Shelby County's case challenges the constitutionality of these requirements.

On Thursday, Democrats encouraged the Supreme Court to uphold Section 5, as there is still evidence of "overt" racism.

"It would be wonderful to say that we have progressed past the need for protection under Section 5 of the Voting Rights Act. Sadly, this is not the case," said Freshman Rep. Marc Veasey (D-Texas), who cited evidence from two years ago in his home state.

"Overt, racially discriminatory tactics were used to isolate and suppress hundreds of thousands of minorities for the purpose of political gain by current partisan leaders of my state," he said.

"Unfortunately in states like Texas, where the minority population is growing very rapidly, and their voting strength is increasing, rather than work to earn the vote of the minority citizens, state leaders would rather suppress voters through racially discriminatory tactics."

Rep. Eddie Bernice Johnson (D-Texas) said the last election showed that racial discrimination is a "persistent reality" in her state, which justifies Section 5.

"If every state would prove to the voters that they are willing not to discriminate, there would not be the need, but that has not happened," she said. "Even states not covered have had difficulty allowing minorities to express themselves.

"I have been victim of discrimination through redistricting and cracking and packing and every other technique than can happen in redistricting. Until we and this country can guarantee that voters will be handled fairly, there's no way that we should be talking about doing away with Section 5 of the Voting Rights Act."

Rep. Sheila Jackson LeeSheila Jackson LeeMerkley leads Dem lawmakers to border amid migrant policy outcry This week: House GOP regroups after farm bill failure Dem lawmaker spars with own party over prison reform MORE (D-Texas) said Houston, Texas, continues to report cases of voter abuse, and said decisions such as whether to eliminate certain school districts still need to be reviewed at the federal level.

"This is no time to eliminate pre-clearance," she said.