A letter from the Voting Section of the Justice Department's Civil Rights Division asks South Carolina for more information about their voter ID law and lays out eight questions about how it will be implemented.
The law requires voters to show a driver's license, military identification or passport as well as their voter registration card at the polls. Monday marked the end of the 60-day review period for the new law.
A coalition of voting rights groups wrote the Justice Department earlier this month to ask it to oppose South Carolina's law.
"South Carolina clearly has not satisfied its burden in showing that its photo voter identification law is neither retrogressive nor discriminatory in its purpose," they wrote.
On Friday, the state Senate's Democratic caucus filed an official objection to the law with the Justice Department.
"This is just wrong," said state Sen. Gerald Malloy. "With all the problems we have in this state relating to the economy, and we end up having a partisan bill that would disenfranchise poor and primarily African-American voters -- this is not where we want our state to go."
Haley has insisted the law isn't meant to discriminate against any group and that showing a photo ID at the polls is common sense.
"If you can show a picture to buy Sudafed, if you can show a picture to get on an airplane, you should be able to show a picture to make sure that we do what is incredibly inherent in our freedoms and that is the ability to vote," Haley said.
That's a talking point that Democrats have been pushing back against in recent months.
"You wanna know something? Getting a video from Blockbuster is not a constitutional right. Getting liquor from the liquor store is not a constitutional right," Rep. Gwen Moore (D-WI) said at at news conference on Capitol Hill in July.
South Carolina is one of several states which passed or considered voter ID laws this year. According to the National Conference of State Legislatures, 14 states currently have photo voter ID laws. In 2011, legislation was proposed in 20 states which did not have voter ID laws and 14 of 27 states that already had non-photo ID laws considered legislation to require photo ID.
Four of those states -- Alabama, South Carolina, Tennessee and Texas -- enacted a photo ID requirement, but those laws can't take effect in South Carolina and Texas until DOJ approves of the measures. Governors in Minnesota, Missouri, Montana, New Hampshire and North Carolina all vetoed new photo ID laws in 2011. Full coverage here.