Gaye's relatives and Bridgeport Music bosses, who own the rights to George Clinton's band Funkadelic's compositions, claim the summer smash bears striking similarities to Gaye's Got to Give It Up and Funkadelic's track Sexy Ways.
The plaintiffs' accusation prompted Thicke, his producer Pharrell Williams and his rap collaborator T.I. to take pre-emptive legal action to protect their song against a possible copyright claim by Gaye's heirs.
Williams recently defended his work, admitting he's a big fan of Gaye but insisting the two compositions are "completely different" and "not even in the same key".
Now Wonder, who has faced similar allegations over the years, has weighed in on the controversy and offered his thoughts to Gaye's family - and he's convinced a costly court battle will only result in a loss of funds for his pal's estate.
He tells Tmz.com, "I don't think it's a steal (sic) from Marvin Gaye... Let me say this to you... I think objectively... the groove is very similar, but you gotta remember he (Williams) is a big fan of Marvin Gaye, so that's Ok. But the song is not the same song, so if the family should hear this, don't let your lawyer, whomever, get you into losing money on something that's not worth it (sic)."