The 1985 Senate hearings
On September 19, 1985, after several weeks of intense media pressure exerted by the PMRC, the Senate Commerce Technology and Transportation Committee organised a series of hearings to investigate the pornographic content of rock music. This was the first official event directly imputable to the PMRC. Several rock personalities were called upon to give evidence:
Frank Zappa, Dee Snider, from the group Twisted Sister and John Denver. The RIAA, the Recording Industry Association of America, also attended the hearings. They were primarily meant as a symbolic show of force since no legislation had been contemplated at the outcome, the Committee being aware of the complex constitutional issues involved. Nevertheless the PMRC believed the mere threat should prove sufficient to urge the record industry to more caution. And indeed, on November 1, 1985, before the hearing were even over, the RIAA substantially acquiesed in the PMRC's demands, save a few alterations to the inital project.

Consequently, the RIAA asked its members (85% of all American record companies, including all the majors) to choose between two solutions: either to affix a warning label or to print the lyrics on the sleeve. In most cases, record companies chose the warning label. Thus, from January 1986 to August 1989, out of 7500 albums released, 49 displayed some kind of warning message (in the same period, the PMRC had considered 121 records offensive), including re-released album by blues artist Sonny Boy Williamson. Among the first was French artist Serge Gainsbourg's Love on the Beat for whom the label was altered into 'explicit French lyrics'!

There is another account of the story. Since 1982, the RIAA had been trying unsuccessfully to have a bill passed in Congress (HR 2911 and S 1711, the Home Audio Recording Tax) a bill which would have established a tax on blank audio tapes, at the rate of 1c. per minute, yielding approximately $250.000.000 a year, an enormous stake from which only the record companies and a few stars would have benefited, due to the appropriation system considered (Kennedy, 1985, p.135). As early as May 1985, the RIAA had accepted to meet the leaders of the PMRC to discuss their demands. This was followed by the hearings we have mentioned. 

As it happened, four of the senators who sat at the hearings of the Commerce Committee (Sen. Packwood, Sen. Gore, Sen. Thurmond and the chairman, John C. Danforth, Republican Senator of Missouri) not only also sat at the ad-hoc committee which worked on the HR 2911 bill, but were besides married to PMRC's officials. On November 1, 1985, the RIAA signed the agreement with the PMRC; a few months later, the tax was voted. Which consideration overrode the other? 
The fear of an hypothetical legislation on sex in rock music or the prospect of a substantial bounty? Questioned on the subject, Paul Russinoff, an RIAA official, stuck to the official position that the labeling compromise was the lesser of two evils, the only way to avoid coercitive legislation.3 This is what the RIAA annual report confirms: 'the  Parental Advisory Program continues to offer a sound, sensible and constitutionally legal alternative to censorship legislation.' (RIAA, 1994, p.18) To be fair, the RIAA yielded on the main points only and firmly rejected the PMRC's other demands (a rating system and a ban on explicit covers).