Robin Thicke -- I Was Too Wasted on Vicodin to Write 'Blurred Lines'

4:34 P.M. PDT -- Thicke's attorney Howard King tells TMZ ... “Robin's moment of personal vulnerability is being exploited in the hope of diverting attention from the obvious weakness of their legal claim.”

Robin Thicke was wasted on Vicodin and booze when he helped create "Blurred Lines" ... and that's his defense to allegedly ripping off Marvin Gaye.

Thicke sat for a deposition in the case where Gaye's family sued him for allegedly lifting Marvin's song, "Got to Give it Up."

The lawyer for Gaye's family asked Thicke if he was present when Pharrell created "Blurred Lines." Thicke responded, "I was high on Vicodin and alcohol when I showed up at the studio." He goes on to say he was so out of it he really wasn't involved in the creative process.

Thicke then kind of throws Pharrell under the bus in the depo, saying, "The reality is, is that Pharrell had the beat and he wrote almost every single part of the song."

Thicke has a problem ... he gave a GQ interview where he said, "Pharrell and I were in the studio and I told him that one of my favorite songs of all time was Marvin Gaye's 'Got to Give it Up.' I was like, 'Damn, we should make something like that, something with that groove.'"

Thicke had a great answer for his GQ interview, telling the lawyer, "With all due respect, I was high and drunk every time I did an interview last year."

In fact, Thicke said, "Every day, I woke up, I would take a Vicodin to start the day and then I would fill up a water bottle with vodka and drink it before and during my interviews."

Robin says he's now drug free, telling the Gaye family lawyer, "I've been sober for the last 2 months ... When your wife leaves you, it gives you good reason to sober up."