Supreme Court Justice Stephen Breyer warned Monday that his colleagues might be too eager to overturn earlier rulings that he said deserve respect as established precedent, mentioning a key abortion ruling as one of them.

"The law can retain the necessary stability only if this court resists that temptation, overruling prior precedent only when the circumstances demand it," Breyer wrote.

His comments came in a dissent as the court, by a 5-4 vote, ruled that a state cannot be sued in the courts of a different state unless it gives its permission. The ruling came in a taxpayer lawsuit filed in Nevada against California.

Overturning a 40-year-old precedent, the Supreme Court said the Constitution does not allow lawsuits against the states without their consent. Writing for the majority, Justice Clarence Thomas said state immunity is an essential part of federalism.

But Breyer said the ruling caused him "to wonder which cases the court will overrule next."

He said overturning longstanding precedent requires a special justification, beyond a finding that an earlier court got something wrong. "[L]ater-appointed judges may come to believe that earlier-appointed judges made just such an error ... " he wrote. "But the law can retain the necessary stability only if this court resists that temptation."

Among cases he mentioned that deserve respect as precedent was the court's 1992 ruling in Planned Parenthood v. Casey, which upheld the fundamental right to an abortion first stated in Roe v. Wade.

It is dangerous, Breyer said, "to overrule a decision only because five members of later court come to agree with earlier dissenters on a difficult legal question."

The court's new conservative majority has emboldened opponents of abortion, who are pushing states to enact new restrictions in hopes of getting a case to the Supreme Court that would challenge Roe's core holding.

"Pro-life forces haven't been this energized in decades," said Tom Goldstein, a Washington, D.C., lawyer who argues frequently before the court. "They believe that they have a Supreme Court that's on their side and they are not going to be incrementalists."