The legal move is preemptive, after Marvin Gaye's family and Bridgeport Music - which owns several compositions by the group Funkadelic - complained the trio's hit summer was too similar to the late Motown singer's track, 'Got to Give It Up' and the funk group's 'Sexy Ways'.
According to The Hollywood Reporter, court documents read: ''Plaintiffs, who have the utmost respect for and admiration of Marvin Gaye, Funkadelic and their musical legacies, reluctantly file this action in the face of multiple adverse claims from alleged successors in interest to those artists.
''Defendants continue to insist that plaintiffs' massively successful composition, 'Blurred Lines', copies 'their' compositions.''
The late Marvin Gaye's family say 'Blurred Lines' has the same ''feel'' and ''sound'' as 'Got to Give It Up' , while those in the Funkadelic camp believe the catchy tune is too similar to the band's 'Sexy Ways'.
However, the lawsuit cites: ''There are no similarities between plaintiffs' composition and those the claimants allege they own, other than commonplace musical elements. Plaintiffs created a hit and did it without copying anyone else's composition.''
Robin and his fellow hitmakers are heading to court to try and prove they didn't intentionally copy anyone's songs and to avoid paying a monetary settlement.
'Smalls Change (Meditations Upon Ageing)' arrives in April.
The two awards have made for a great 72nd birthday present for the country music icon.