The Texas Oil and Gas Association said it filed a case against the city of Denton after voters backed an initiative to ban hydraulic fracturing.

Denton voters passed a special measure on the midterm ballot that prohibits hydraulic fracturing within city limits. It's one of the first such local measures in the country to get voter approval.

Denton sits on top the Barnett shale play in Texas, which at the end of 2013 was in the top tier in terms of production from shale basins in the United States.

Thomas Phillips, former chief justice of the Texas Supreme Court and now a lawyer representing the Texas Oil and Gas Association, said a suit was filed in Denton County district court against the measure.

"The association does not believe that they may enact ordinances that outlaw conduct, like hydraulic fracturing, that has been approved and regulated by state agencies such as the Texas Railroad Commission [the state's energy regulator] or the Texas Commission on Environmental Quality," he said in a statement Wednesday.

When the issue was approved for the November ballot, Denton Mayor Chris Watts said the city was frustrated by a legacy of hydraulic fracturing in the area.

There are more than 250 active gas wells in a city with just over 120,000 residents.

Supporters of hydraulic fracturing say it's a source of economic stimulus and energy security. Energy prices are at historic lows in part because of the gains from shale plays like Barnett.

Cathy McMullen, president of Frack Free Denton, said hydraulic fracturing poses a long-term threat to resident's well being.

"We lawyered this ban every which way before launching this effort," she said in a statement. "And we consulted legal precedents for Texas home rule cities like Denton. And we're confident it will stand up."