Following major Election Day victories for anti-fracking campaigners in Colorado last month when four cities voted to ban the controversial oil and gas drilling technique, fossil fuel industry players have refused to accept defeat and are initiating legal battles that could potentially see those voter-approved referendums overturned.

As Al Jazeera-America reports, the Colorado Oil and Gas Association (COGA) filed a lawsuit this week against the towns of Lafayette and Fort Collins, arguing that voters violated a state law they say protects the fracking industry when they passed their respective referendums.

“It’s not a surprise that the Colorado Oil & Gas Association would take this position,” Laurie Kadrich, director of community development and neighborhood services for the city of Fort Collins, told Bloomberg.

“As a city, we have a responsibility to defend the voter-approved ordinance, so we’ll be looking into the contents of the lawsuit and we’ll respond appropriately,” Kadrich said.

Another Colorado city that passed a ban on fracking, Broomfield, which narrowly passed its referendum in a ballot recount, is facing a separate lawsuit filed Tuesday by Broomfield Balanced Energy Coalition (BBE), which charges city officials of mishandling the ballot counting.