The filing made Tuesday seeks compensatory damages from the company and a change in practices.
Plaintiffs' lawyer Stephen DeNittis says the company should either make their sandwiches 12 inches long or stop advertising them as footlongs.
He said he's measured sandwiches from 17 area shops and not one has been 12 inches long.
The issue got widespread attention last week when a man posted a photo of a sandwich and a ruler on the company's Facebook page.
Milford, Conn.-based Subway did not immediately return a call to The Associated Press.