Associated Press reports: 

Two Texas residents backed by a conservative legal group have filed a federal lawsuit in Austin challenging how state Senate voting districts were drawn, according to a published report Tuesday.

…The lawsuit argues that the way districts were drawn was unconstitutional since it was based on total population. The districts should have been drawn only based on the number of eligible voters, excluding children, felons and noncitizens, the lawsuit says. It also says that districts with fewer eligible voters have more influence than those in districts with more eligible voters, which is unconstitutional.