The American Civil Liberties Union is suing the City of Defiance, alleging its ban on sidewalk messages shouldn't apply to chalk messages and also violates free speech rights.
At issue is a city law that prohibits disfiguring sidewalks by painting words, names or ads.
The ACLU's Ohio chapter argued in a federal lawsuit Tuesday that the law is unconstitutional and asked a judge to stop its enforcement.
It also argues the law shouldn't apply to chalk, which is not permanent.
The issue arose last year when members of an Occupy group were threatened with arrest for writing chalk messages the night before the city's annual Halloween parade.
City law director David Williams hadn't seen the complaint. He previously has said the ban has nothing to do with messages' content.