WASHINGTON — Justice Antonin Scalia has never been shy about saying what he thinks and never reluctant to criticize those he disagrees with.

For more than a quarter-century, the high court’s term has nearly always ended with a rush of opinions in late June and a fiery dissent from Scalia.

His colleagues sit with tight expressions or distant gazes as Scalia sounds off, his tone one of anger and disgust.

His targets Monday included illegal immigrants and President Obama. Dispensing with what he called the “dry legalities” of the Arizona immigration case, he spoke of its citizens being “under siege” and states feeling “helpless before those evil effects of illegal immigration.”

“Are the sovereign states at the mercy of the federal executive’s refusal to enforce the nation’s immigration laws?” Scalia asked.

Some said it was highly unusual, and perhaps out of line, for Scalia to cite Obama’s announcement in mid-June that he was granting a two-year reprieve to young people who entered the country illegally as children. Obama may have called it “the right thing to do,” Scalia said, but “Arizona may not think so.”

Usually, the justices rely only on what is in the legal record of the case.

Liberal commentators and some law professors said Scalia’s tone was strident and partisan.

He is “sounding more like a conservative blogger or Fox News pundit than a justice,” said George Washington University law professor Jeffrey Rosen.

Paul F. Campos, a law professor at the University of Colorado at Boulder, wrote on Salon about Scalia: “In his old age, he has become increasingly intolerant … and a pompous celebrant of his own virtue and rectitude.”

Edward Whelan, president of the Ethics and Public Policy Center and a former Scalia law clerk, said Scalia “was responding directly to the government’s own argument. Scalia’s basic point was to illustrate that the Arizona law didn’t conflict with federal immigration law but instead was at odds with the current administration’s refusal to enforce federal laws.”

Scalia, now 76 and the court’s senior justice, spoke only for himself. Justices Clarence Thomas and Samuel A. Alito Jr. dissented as well, but did so in separate opinions. It was hard to miss the fact that Scalia’s reproach was directed at an opinion that spoke for Chief Justice John G. Roberts Jr. and Justice Anthony M. Kennedy, the two who are likely to hold the deciding votes in the court’s healthcare ruling, set for Thursday.

Scalia has long been a dominant figure in the court’s oral arguments. His quick wit and sarcastic jibes can ruffle lawyers, particularly those who are arguing for liberal rulings.

It has been much debated, however, whether Scalia’s dissents have helped or hurt his cause. His take-no-prisoners style has won him legions of admirers among conservatives. But he has also alienated some of the court’s moderates, who split with him and went their own way.

In 1989, he criticized Justice Sandra Day O’Connor when she refused to go along with an opinion by then-Chief Justice William H. Rehnquist that would have overturned the Roe vs. Wade decision that legalized abortion. O’Connor said such a decision was premature, since the case before the court involved only minor regulation of abortion. In a full-bore dissent, Scalia said her view was “not to be taken seriously.”

Three years later, Justices Kennedy and David H. Souter joined with O’Connor and broke with Scalia to uphold the abortion right. More recently, Kennedy, O’Connor and Souter voted to uphold gay rights claims, despite fierce dissents from Scalia.

Scalia had a good relationship with Rehnquist. Both conservatives, they almost always agreed on major cases. So far, the same has been true with Scalia and Roberts. The big test will come Thursday, however, when the chief justice begins the announcement of the court’s decision on the constitutionality of the Obama administration’s healthcare law.

david.savage@latimes.com