This whole issue isn’t as simple as it seems on the surface. The “preclearance” requirement in the Voting Rights Act (in Section 5) has a history of litigation in Texas.
Basic info:
https://en.wikipedia.org/wiki/Voting_Rights_Act_of_1965#Section_5_-_Preclearance
The 25-year extension of the preclearance procedure (by Pres. Bush and the Congress in 2006) was challenged in a lawsuit in 2009 in Texas, but the Supreme Court failed to declare preclearance unconstitutional.
https://en.wikipedia.org/wiki/Northwest_Austin_Municipal_Utility_District_No._1_v._Holder
The Bailout Bait and Switch: DOJ’s Last-Ditch Attempt to Rescue Section 5 of the Voting Rights Act (April 18, 2011)
http://www.heritage.org/research/reports/2011/04/the-bailout-bait-and-switch-dojs-last-ditch-attempt-to-rescue-section-5-of-the-voting-rights-act