Jack Shafer takes a look at Rehnquists chronic drug use in Slate:
[F]or the nine years between 1972 and the end of 1981, William Rehnquist consumed great quantities of the potent sedative-hypnotic Placidyl. So great was Rehnquist's Placidyl habit, dependency, or addiction—depending on how you regard long-term drug use—that by the last quarter of 1981 he began slurring his speech in public, became tongue-tied while pronouncing long words, and sometimes had trouble finishing his thoughts. ***Go read the whole article. It is a powerful illustration of "the ugly double standards that excuse extreme drug use by the powerful, especially if their connection is a prescribing doctor, and condemns to draconian prison terms the guy who purchases his drugs on the street."
[A confidential report on Rehnquist's medical history prepared for the Senate Judiciary Committee in 1986] described him as seriously "dependent" on Placidyl from 1977 to 1981. He often consumed three month's worth of the drug in one month before requesting more from Dr. Freeman H. Cary, the attending physician to Congress, who prescribed it. Anonymous sources told the Post that Cary first prescribed Placidyl to Rehnquist in 1971 to help him sleep through his severe back pains, but "Cary reportedly told the FBI that Rehnquist had taken it before." ***
When Rehnquist's drug problem became an issue during the 1986 confirmation hearings, Sen. Orrin G. Hatch, R-Utah, defended Rehnquist in a Post story, saying he got into trouble with Placidyl because he was "a very compliant patient" who "followed the advice" of his doctors. Ah, yes, one of the most brilliant jurists of his time was the victim of his rotten doctors for almost a decade! Are we to believe that one of the court's sharpest minds never availed himself of a Physicians' Desk Reference for independent medical information, or in any way tried to educate himself about the drug he was taking in larger and larger quantities? The Senate Judiciary Committee asked Rehnquist no questions about his drug use, and he was, of course, confirmed as chief justice. The debate over whether Rehnquist's drug use might be relevant to his fitness to serve as chief never got started.