Dayton and Springfield filed lawsuits Wednesday challenging the law requiring a law enforcement officer's presence for tickets to be issued from the cameras. Akron and Toledo earlier filed similar lawsuits in their counties.
Opponents say the law taking effect Monday amounts to a ban because cities can't afford to keep officers at intersections with cameras.
Dayton also asked the Montgomery County judge for an injunction preventing the law from taking effect until the city's challenge is heard.
The state's response asks the judge to deny the injunction and says the home rule challenge isn't likely to succeed.
