The Supreme Court has had divisive rulings this year on the environment, police power and whistleblowers, and the justices are not even through with their hardest cases.
The high court is on a tight deadline to finish before July, when justices begin a three-month break that provides time for traveling, teaching classes, writing books and relaxing.
As usual, justices have left some of the most significant cases to the very end. There are 10 rulings left, on issues from a president's wartime powers, capital punishment, Texas' political boundaries and the insanity defense.
The past year has been a time of change. Chief Justice William H. Rehnquist died and his former law clerk John Roberts succeeded him.
In addition, the influential Justice Sandra Day O'Connor, the first female justice, retired. She was replaced in January by Samuel Alito.
Justice Anthony M. Kennedy has emerged as an important swing voter — a role previously held by O'Connor. Kennedy wrote the term's two biggest death penalty cases, which made it easier for death row inmates to contest lethal injections and to get DNA evidence before the courts.
Kennedy, a centrist put on the court by President Reagan, also blocked conservatives from dramatically scaling back the Clean Water Act. The 5-4 decision preserves government authority to block development on wetlands as long as the wetlands meet Kennedy's test.
"We have entered the era of the Kennedy court. It's striking what a pivotal role Kennedy has come to play," Duke Law School professor Erwin Chemerinsky said.
In conservative victories, Kennedy wrote a 5-4 decision that said public employees do not have free-speech protections for what they say as part of their jobs. He also broke a 4-4 tie to make it easier for police with search warrants to enter homes without knocking or waiting.
Roberts, in his first term as chief justice, has built a firm conservative voting record, but without Kennedy does not have a solid voting block.
"This is not a court that has a clear solid five votes for doing anything that a conservative majority wants to do," said Stephen Wermiel, a law professor at American University.
Roberts has written seven opinions, all but one unanimous. Among them, he bolstered police power to enter a home to break up a fight without knocking first; upheld a church's use of hallucinogenic tea; and found that the government can force colleges to open campuses to military recruiters despite university objections to the Pentagon's "don't ask, don't tell" policy on gays.
The chief justice has encouraged his colleagues to be more unified in their decision-making. So far, justices have been split 5-4 in just seven of the 59 rulings.
The big test, however, is still ahead.
The most significant case of the year challenges the president's power to order military trials for suspected foreign terrorists held at the Navy prison at Guantanamo Bay, Cuba. Roberts cannot participate because he served on an appeals court panel that backed the Bush administration in the case last year.
Two election cases are still to be decided.
Justices have been asked to throw out all or part of a Texas congressional map promoted by former House Majority Leader Tom DeLay, R-Texas. They also will decide how far states can go to limit spending and donations to political campaigns.
Alito is expected to break a tie in the one death penalty case still undecided, a constitutional test of Kansas' death penalty law. The case was argued the first time before O'Connor's departure. A new argument session was held after his arrival.
It is tough to tell the court's direction so early in the tenures of Roberts and Alito, most court-watchers say.
Justices have lined up some significant cases for next fall, on abortion, public school affirmative action and the environment.
"Justices are willing to test the new lineup right away. Next year is where the rubber is going to hit the road," said John Yoo, a University of California, Berkeley, law professor.