The U.S. Supreme Court on Tuesday heard a challenge from a group of Republican voters who claim Arizona’s Independent Redistricting Commission violated the principle of one-person, one-vote when it created districts with more residents
than others.

The commission was made up of two Republicans, two Democrats and one unaffiliated member. It was tasked with drawing legislative district boundaries for the state following the 2010 U.S. Census. The commission worked on various options, ultimately tailoring its plan to be compliant with the Voting Rights Act. 

At the time, Arizona was covered by a VRA provision mandating that its legislative districts be "pre-cleared" by either the attorney general or a federal three-judge panel. 

The resulting district boundaries sparked a lawsuit by voters who claim the maps favor Democrats by diluting Republican votes in certain districts and violate the Equal Protection Clause. 

A three-judge federal court ruled in favor of the commission, finding that -- while some of the members were driven in part "by a desire to improve Democratic prospects in the affected districts" -- the commission was primarily motivated by trying to comply with the VRA. 

However, after the case had been argued and while the district court's opinion was pending, the Supreme Court decided Shelby County v. Holder, striking the portion of the VRA which required Arizona to get pre-clearance for its district boundaries. 

The lower court ultimately ruled that Shelby did not apply retroactively to the Arizona case.  The bottom line question for the justices will be just how far a state can deviate from the "one-person, one-vote" principle in the interest of addressing other concerns.

The second case before the Supreme Court on Tuesday originated in Texas, where state senate districts are based on overall population numbers. 

Two voters, from two different state districts, are suing based on the argument that districts should be drawn according to the number of eligible voters in a geographic area -- not overall population numbers. The argument goes:  the votes of eligible voters are diluted in districts full of ineligible residents like illegal aliens and felons. 

Critics of the lawsuit say it makes no sense to disregard those who cannot vote but still need representation, such as children and legal permanent residents. 

There's also the question of how Texas would accurately assess how many ineligible residents live in any particular area. Once again, the case will require the justices to look at the concept of "one-person, one-vote" against the backdrop of Equal Protection Clause consideration. 

Decisions in both cases are expected in June 2016.