Updated

A gun-rights activist is taking the city of Phoenix back to court over its refusal to put up a bus-stop ad that declares "Guns Save Lives."

The case is as much about the First Amendment as it is about the Second. The Arizona Republic reports that the three-year legal battle is heading to the Arizona Court of Appeals on Tuesday.

The decision could have sweeping implications for free speech in the state, and on whether advertisers should be limited in what topics they can and cannot address on city property.

The battle started when the city removed 50 of the ads, put up by activist Alan Korwin, from city bus stops.

Phoenix claims the signs violate its policy banning "non-commercial" advertising at transit stops.

But Korwin and a conservative watchdog group are joining up with the American Civil Liberties Union to argue against those restrictions. While Phoenix is hoping to avoid controversy by barring political messages at city bus stops, Korwin's legal team and supporters argue that the state offers more expansive free-speech protections, according to the Arizona Republic.

The city reportedly allowed Korwin to put up a slightly different ad, which said: "Guns Stop Crime."

But Korwin argued this was just part of their "censoring" process.