The Townsend family said in the suit that Sheeran repeatedly used elements from "Let's Get It On" in his Grammy-winning hit "Thinking Out Loud."
"The Defendants copied the 'heart' of 'Let's' and repeated it continuously throughout 'Thinking,'" the Townsend's allege in the suit.. "The melodic, harmonic, and rhythmic compositions of 'Thinking' are substantially and/or strikingly similar to the drum composition of 'Let's.'"
Townsend's estate is asking for a jury to decide if damages are owed.
This is the second copyright suit for Sheeran, who is facing $20 million in damages for reportedly illegally sampling a song written for X Factor season 7 winner Matt Cardle to use in his hit "Photograph."
Sheeran has yet to comment on either suit.