Two of Gaye's children have now responded by filing a countersuit, in which they claim that Thicke also stole from Gaye's 1976 "After the Dance" track to create "Love After War."
"We have investigated this matter fully, took great care with the allegations and have put together a comprehensive pleading that speaks for itself," said Richard Busch, the attorney representing the Gaye family. "We look forward to presenting this case to the court and jury who can hear the songs themselves."
Thicke and his collaborators maintained in August that "Blurred Lines," arguably last summer's biggest hit, was merely "reminiscent" of Gaye's "sound."
"Being reminiscent of a sound is not copyright infringement," they said in the suit. "The intent in producing 'Blurred Lines' was to evoke an era. In reality, the Gaye defendants are claiming ownership of an entire genre."
In court documents obtained by the Hollywood Reporter, the countersuit accuses Thicke of having a "Marvin Gaye" fixation. They cite multiple media sources -- including The New York Times and Rolling Stone -- who have compared Thicke's hit to the late singer's song.
Gaye's family also sued song publisher EMI for protecting the copyrights to Gaye's music.
Notable deaths of 2014 [PHOTOS]