A free speech battle over political messaging at Phoenix bus stops goes to court on Tuesday morning. The case will be heard at the state court of appeals and could have wider repercussions, legal experts say.

In 2010, Alan Korwin commissioned 50 advertisements at Phoenix bus shelters.

“Guns save lives,” the ads said.

Korwin, a publisher who sells books about gun laws, said the messaging promoted gun safety and training, but the ads were only up for nine days before the city took them down, he said.

“We’ve been discriminated against in a very partisan way,” Korwin said. “They approve some ads they like, and they disapproved of our ads because they don’t like them.

The city declined to comment for this story, but Korwin said Phoenix disapproved of the ads, because they made a political statement and were not focused on a commercial enterprise. The case will examine what discretion cities have over advertizing on public property.