The controversy began last year, when the media began questioning why the Chicago Transit Authority was carrying advertisements for Grand Theft Auto IV in the wake of then-recent violent events, though the ads themselves weren't violent in any way.

Shortly after, the Chicago Transit Authority pulled the advertisements, and, after a lawsuit, reinstated the ads while noting that it would no longer carry ads for mature-rated games once it had fulfilled its contract with Grand Theft Auto publisher Take-Two.

The ESA claims that the CTA is "unfairly targeting the entertainment software industry by enacting an ordinance that selectively bans advertisements of computer and video games rated 'Mature 17+' (M) or 'Adults Only 18+' (AO)," amongst other points.

In a press release announcing the suit, the ESA explained:

The ESA's suit contends this new ordinance unconstitutionally "restricts speech in a public forum that is otherwise open to all speakers without a compelling interest for doing so." In addition, the Complaint argues that the ordinance impermissibly discriminates on the basis of viewpoint and ignores less restrictive means of achieving the supposed ends of the ordinance.

The ESA also stated that the CTA's ordinance is unnecessary because game-related marketing is already subject to the Entertainment Software Rating Board's Advertising Review Council (ARC), which strictly regulates computer and video game advertisements that are seen by the general public. The Entertainment Software Rating Board (ESRB) assigns content ratings to computer and video games, which, in turn, are displayed on the advertisements for those games.

"Courts across the United States, including those in the CTA's own backyard, have ruled consistently that video games are entitled to the same First Amendment protections as other forms of entertainment," argued ESA CEO Michael Gallagher. "The CTA appears unwilling to recognize this established fact, and has shown a remarkable ignorance of the dynamism, creativity and expressive nature of computer and video games. The ESA will not sit idly by when the creative freedoms of our industry are threatened."