During his 19 years on the high court, the chief justice shepherded the court in a more conservative direction.
The end of Rehnquist's tenure, which included 14 years as an associate justice appointed by President Nixon, creates two vacancies at once on the court for the first time since 1971.
Rehnquist's time as chief justice marked a modest revival of states' rights and a gradual elevation of the concept that individual rights often must give way to police power when the two come into conflict. That philosophy revealed itself in disputes involving the Internet, privacy and free speech.
Rehnquist joined Justice Sandra Day O'Connor in 1997 in saying that the amounted to "little more than an attempt by Congress to create 'adult zones' on the Internet."
In a dissent, the duo said the law's restrictions on "indecency transmission" were appropriate and should be upheld. (They did agree, however, that other sections of the law were troublesome and did not comply with the First Amendment.)
Six years later, when the high court returned to the concept regulating sexually explicit material online, Rehnquist again voted with in a minority that sided with the federal government. A dissent (Click for PDF) that he joined argued the Child Online Protection Act imposes only a "modest additional burden" on adult sites and should be upheld as constitutional.
In a 2003 case involving library filtering, Rehnquist wrote the majority opinion himself. Encouraging libraries to block pornography "does not violate their patrons' First Amendment rights," he said.
On police searches, too, Rehnquist tended to side with law enforcement. One 2001 case dealt with whether police could use a thermal imaging device--without a warrant or court approval--to peer inside private homes for evidence of marijuana growing.
The majority said police must obtain a search warrant. But Rehnquist joined the dissenters who quipped that the privacy argument was "quite difficult to take seriously."
While Rehnquist often sided with fellow conservative Antonin Scalia, the two didn't always see eye to eye. In a June decision dealing with whether cable providers would be forced to share their networks with rivals, the chief justice joined the majority that sided with the cable companies.
In a blistering dissent, Scalia and two other justices upbraided their colleagues for paying too much attention to "regulatory history" and the views of government bureaucrats instead of the plain text of the law.
With the retirement of Justice O'Connor and President Bush's nomination of John Roberts as her successor, speculation among bloggers quickly turned to whether Roberts would be picked for the chief justice position. Orin Kerr, who recently clerked for Justice Anthony Kennedy, speculated that Roberts would be appointed chief justice, while others argued the White House would not want to risk the delay that might cause.
Bush said on Sunday that he "will choose in a timely manner a highly qualified nominee to succeed Chief Justice Rehnquist," but without offering details. It wasn't immediately clear whether a Senate Judiciary hearing on Roberts' appointment scheduled for Tuesday would be postponed because of funeral services.