WASHINGTON — Last June, the Supreme Court term ended with restraint and a cliffhanger, as the court left the Voting Rights Act intact and ordered re-argument in Citizens United, the big campaign finance case.

A year later, the profile of the court led by Chief Justice John G. Roberts Jr. is fundamentally changed. Judicial minimalism is gone, and the court has entered an assertive and sometimes unpredictable phase.

That will only intensify with the retirement of Justice John Paul Stevens, a 35-year veteran of the court and the leader of its liberal wing, and his likely replacement by Elena Kagan, the solicitor general, whose confirmation hearings in the Senate are under way this week.

Roberts, who joined the court five years ago, took control of it this year, pushing hard on issues of core concern to him, including campaign finance, gun rights and criminal procedure, even as he found common ground with his colleagues, including some liberals, on an array of other issues.

He was in the majority 92 percent of the time, more than any other justice. Last year that distinction went to Justice Anthony M. Kennedy, who is often regarded as the court’s swing vote.

"More than in any other year since he became chief justice, this has truly become the Roberts court," said Gregory G. Garre, who served as solicitor general in the administration of George W. Bush and is now at Latham & Watkins.

The centerpiece of the last term was, of course, the 5-4 decision in Citizens United, allowing unlimited corporate spending in elections. The ruling generated waves of criticism, including comments from President Barack Obama at the State of the Union address in January. It was the most controversial decision since the Rehnquist court handed the presidency to Bush a decade ago in Bush v. Gore, and it was easily the most debated of the Roberts court era so far.

The outcry did not chasten the court.

"I don’t think it made the least bit of difference to the five justices in the majority," said Paul D. Clement, who also served as solicitor general in the second Bush administration and is now with King & Spalding.

The Citizens United decision contained not a trace of minimalism, and it showed great solicitude to the interests of corporations.

"They’re fearless," Lisa S. Blatt, who served in the solicitor general’s office for 13 years before joining Arnold & Porter last year, said of the justices in the majority. "This is a business court. Now it’s the era of the corporation and the interests of business."

Some of the issues that have most engaged the court in recent years were missing this term, which included only one decision concerning national security and none about abortion or about prisoners held at Guantanamo Bay, Cuba.

The court continued its push to broaden Second Amendment rights, ruling Monday that the amendment’s protections apply to state and local gun control laws as well as to federal law.

And the justices further limited the rights of criminal defendants. Last term, the court narrowed earlier decisions barring the use of evidence obtained through police misconduct.

This term, the court was focused on the Miranda rule, which requires the police to warn suspects in custody of their rights before interrogating them. In three decisions this term, the court allowed the police to vary the language of the warning, insist that suspects speak in order to protect their right to remain silent and resume questioning after suspects have invoked their rights.

"The court continues its march to restrict exclusionary rules," said Jeffrey L. Fisher, a law professor at Stanford who argues frequently before the court. "The court is refusing to exclude what the court thinks is reliable evidence in criminal cases. None of the conservatives are unpredictable in any of these cases. They’re leading the retreat."

The court acted quickly — and, some critics said, rashly — in intervening in cases without full briefing and argument. In January, it halted the broadcast of the trial over same-sex marriage in San Francisco partly on a rationale it seemed to disavow five months later. This month, it sent elections in Arizona into disarray by barring the use of a 12-year-old campaign finance law.

Thomas C. Goldstein, a lawyer with Akin Gump Strauss Hauer & Feld and the founder and publisher of Scotusblog, which prepared comprehensive statistics about the court, said the court’s five more conservative members — Roberts and Kennedy, Antonin Scalia, Clarence Thomas and Samuel A. Alito Jr. — were simultaneously aggressive and selective.

"I’m struck by the ways in which the conservatives seem to be willing to take significant steps on core questions," Goldstein said, noting campaign finance and Miranda rights as examples. "In other cases, the five more conservative members of the court don’t seem to be prepared to press every advantage."

Indeed, Roberts provided a sixth vote in the decision banning life-without-parole sentences for juvenile offenders, though on a narrower ground than the majority. He was the only justice to join every part of Justice Ruth Bader Ginsburg’s majority opinion casting doubt on the conviction of Jeffrey K. Skilling, the former Enron executive.

And the chief justice joined the court’s four more liberal members — Stevens, Ginsburg, Stephen G. Breyer and Sonia Sotomayor — in Breyer’s majority opinion affirming congressional power to authorize the civil confinement of sex offenders. Kennedy and Alito filed concurrences, making the vote in the case 7-2.

"The term as a whole will go down principally for what we see in the evolution of John Roberts and his leadership of the institution," Goldstein said. "He cares about the position of the court in American life. He is not pressing every ideological question but is willing to cross over."

Roberts is not wedded to a single judicial methodology like the originalism and textualism that are the touchstones for Scalia and Thomas.

Scalia and Thomas, who voted together 92 percent of the time — the highest of any pair of justices — often take positions based on jurisprudential principles without regard to the outcome in a particular case. In criminal cases, Clement said, "It’s striking how often if the court gets to a pro-defendant result the majority includes Justice Scalia."

Roberts and Alito, by contrast, can appear more pragmatic.

Nor does Roberts seem as interested in exploring the limits of federal power as Chief Justice William H. Rehnquist, who died in 2005, and Justice Sandra Day O’Connor, who retired in 2006, had been.

"Federalism has less salience with this court than it did with the Rehnquist court," Sri Srinivasan, who served in the solicitor general’s office and is now with O’Melveny & Myers, said at a Chamber of Commerce briefing last week.

There were more surprises and unusual alliances in this term than in most recent ones. Stevens, for instance, joined the court’s five more conservative members in voting to uphold provisions of a law making it a crime to provide even benign and intangible aid to foreign terrorist organizations.

Sotomayor’s replacement of Justice David H. Souter last year turned out to do almost nothing to alter the court’s ideological balance. She voted with Ginsburg and Breyer 90 percent of the time. Some liberals had feared that her experience as a prosecutor would make her skeptical of some claims from criminal defendants, but she voted in a reliably liberal direction in those and other cases. Her first major dissent was in a case narrowing Miranda rights.

Similarly, the replacement of Stevens by Kagan, a 50-year-old who has never served as a judge, would in all likelihood do little to affect the voting lineups on the court. But the departure of Stevens nonetheless represents a turning point.

"The intellectual, emotional, political, tactical leader of the left is leaving," Goldstein said.

The court is also losing a bit of a maverick who was often skeptical of government power. With Kagan, Fisher said, "we could be moving more to a court that is willing to defer to the executive."

Seniority has privileges at the court. The senior justice speaks second at the court’s private conferences, after the chief justice. If the chief justice is not in the majority, the next-most-senior justice assigns the majority opinion.

"Stevens’ seniority and experience on the court really carries a lot of heft," said Fisher, who served as a law clerk to Stevens. "Even if the exact same person could be reincarnated tomorrow as a junior justice, it would still be a huge loss."

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