The attorney representing both victims says the civil suit could seek millions of dollars.
It was a packed crowd that night and the lawsuit alleges the singer lost control when his microphone was cut off at the end of the night.
The attorney handling the high-profile case says his client, Detroit Sergeant Robert Avery, was punched in the face and assaulted, causing serious internal injuries and also requiring him to have hip surgery.
Attorney Mike Morse said, "The sergeant on the Detroit Police Department for 22 years ... was at this concert protecting not only Mr. Neverson but the public. Robert Avery's doctors have said he will never work again as a police officer because of the injuries that Tremaine Neverson impacted on him that evening. He's a family man with kids, it's horrible."
A photographer was also allegedly hit with a mic stand in the back of the head.
Songz whose legal name is Tremaine Neverson, pleaded guilty to two counts of disturbing the peace in a criminal case and was sentenced to 18 months of probation.