NEW YORK, NY - AUGUST 25: Musician Robin Thicke seen on the streets of Manhattan on August 25, 2013 in New York City.  (Photo
Michael Stewart/WireImage

Two of Marvin Gaye's children have officially filed a copyright infringement lawsuit over Robin Thicke's song of the summer, "Blurred Lines."

The suit targets Thicke, his "Blurred Lines"collaborators and Sony-ATV. They claim "Blurred Lines" is a rip-off of Gaye's 1977 hit "Got to Give It Up" and that label EMI—which is owned by Sony-ATV— failed to protect Gaye's legacy.

The heirs filed the lawsuit as a counter-claim to the pre-emptive suit filed by Robin Thicke, Pharrell and T.I. back in August. The artists decided to strike first, before an actual lawsuit even existed, in the face of legal threats from Gaye's family.

Gaye's children, Nona Marvisa Gaye and Frankie Christian Gaye, are also going after another Thicke song, 2011's "Love After War," which they claim copied their father's 1976 track "After the Dance."

A large part of the suit is aimed at EMI—who the Marvin Gaye heirs contractually entrusted with his music catalog after his death. They claim that EMI should have pursued a copyright infringement lawsuit themselves after the release of "Blurred Lines." EMI is being sued for breach of contract and trust agreements. 

EMI's parent company, Sony-ATV, also represents Pharrell's songs and the suit states that the label has purposefully sided with Pharrell due to the conflict of interest.

"This conflict has resulted in EMI's intentional decision to align themselves with the ("Blurred Lines") writers, without regard to the harm inflicted upon the rights and interests of the Gaye Family, and the legacy of Marvin Gaye," the lawsuit says.

Sony-ATV responded in a statement with the following: 

"While we have not yet seen the claims by the Gaye family against EMI, we have repeatedly advised the Gaye family's attorney that the two songs in question have been evaluated by a leading musicologist who concluded that "Blurred Lines" does not infringe "Got To Give It Up.""

The Gaye children involved are seeking up to $150,000 per infringement in addition to a portion of all royalties made from "Blurred Lines" and "Love After War."