Talk to Buffy Sainte-Marie about that. It took her about 10 years to get them to surrender her file, but they finally did. It turned out to have nothing in it whatsoever except a mountain of innuendo.

(she was effectively blacklisted off all North American radio stations for about 10 years at the potential height of her career. That's how you kill a musician's record sales.   Thank Lyndon Johnson's administration for that. As LBJ reputedly said, "Methinks the lady doth protest too much...")