The court's majority framed its decision as needed to preserve judicial independence.
Adept at working with the Democratic Legislature but repeatedly stymied by the court, Christie has expended political capital to nominate conservative justices. Yet he has only been able to seat one nominee, Anne Patterson, who supported the governor's position in Tuesday's 3-2 decision.
Two of Christie's other nominees to the court were rejected by Senate Democrats - the only two times that the Legislature has declined to confirm a high court nominee since the state constitution was ratified in 1947.
While there's a stalemate over the court's two vacancies, Christie and Democratic leaders appear to be on the same page about how to deal with Tuesday's decision.
Senate President Stephen Sweeney (D., Gloucester), who muscled the benefits reform law through the Legislature last year despite fierce opposition from unions and their Democratic allies, said Tuesday that he will get the votes needed to put the matter on the November ballot as a constitutional amendment.
"It is not fair for every employee in the State of New Jersey to have to pay for health care and pensions and have 400 or so people not pay," Sweeney said, referring to the number of judges and justices. "It's not fair to the guy cleaning the streets. Every single person working in this government is as important as the next person, so they all have to contribute."
At a news conference in Atlantic City, Christie also endorsed putting the issue to voters in November.
"It's typical of an activist liberal court," he said. "That's not what judges should be doing. Salary means salary. Salary does not mean benefits."
By the end of next week, the Assembly and Senate are expected to convene to vote on a bill putting a proposed constitutional amendment on the November ballot. If three-fifths of each legislative house approves the bill, voters could effectively override the court's decision and amend the constitution to force judges and justices to pay for more their pensions and health benefits.
The issue is a constitutional one because the state constitution - in order to inoculate them from political payback from a governor or legislators - bars judges' salaries from being lowered.
In mandating higher payments for pension and health benefits, the law effectively lowered salaries by about $17,000, the justices said. It increased pension contributions for judges and justices from 3 percent of their salary to 12 percent, and health care contributions from 1.5 percent of salary to 35 percent of the premium.
The justices said the law can be applied to those appointed after it went into effect, but by effectively lowering a judge's salary midterm it violates the constitution, which states that judges' "salaries . . . shall not be diminished during the term of their appointment."
The state bar association hailed the decision, with Kevin P. McCann, the group's president, releasing a statement saying the decision means judges "will remain free from political retaliation when judges make an unpopular but just decision."
Although the public and legal battles between the Christie administration and the state's high court were not detailed in Tuesday's opinion, the majority wrote of the importance of an independent judiciary - citing the Declaration of Independence, Alexander Hamilton, and an 1844 iteration of the state constitution.
Justice Barry Albin, Justice Jaynee LaVecchia, and Judge Dorothea O'C. Wefing, who is temporarily assigned to the court, wrote this in their majority opinion: "No court of last resort - including the U.S. Supreme Court - has upheld the constitutionality of legislation of this kind."
The case went to the Supreme Court after a lower court sided with a Superior Court judge who sued over the law.
Christie didn't just target judges with the benefits law. Hundreds of thousands of public employees, from teachers to police to those who work in his administration, were affected.
He said it was intended to help control property taxes and bring public worker benefits in line with those in the private sector.
The justices writing in the majority acknowledged the state's fiscal problems, but said a court that cannot protect its own independence cannot protect the people. They added: "Simply stated, any solution to the state's serious fiscal issues must conform to the requirements of our constitution."
A dissenting opinion by Patterson, the Christie appointee, said that nothing in the 1947 state constitution specified that "salary" includes pension and health benefits:
"We consider a law that governs the pension and health benefit contributions of more than one-half million state and local government employees. It does not discriminate against justices and judges. I cannot agree with the majority that judicial independence is under assault, or even implicated, by virtue of the Legislature's action."
Justice Helen E. Hoens joined Patterson in the dissent, and Chief Justice Stuart Rabner recused himself from the case and gave no reason.
LaVecchia, appointed by Republican Gov. Christie Whitman, voted with the majority. LaVecchia's political leanings have become a point of controversy over the tradition of maintaining a partisan balance among the court's seven members.
Democrats say she is a Republican, having worked for two Republican governors and donated to Republican candidates. That would mean there were three Republican justices.
But Christie says she is an independent - she is not affiliated with either party - and so there are just two Republicans. Therefore, he says, he is entitled to appoint two more Republicans to the court. This is the crux of the stalemate.
Christie will undoubtedly cite LaVecchia's ruling to bolster his argument.
Contact Matt Katz at 609-217-8355, email@example.com, or follow on Twitter @mattkatz00. Read his blog, "Christie Chronicles," at www.philly.com/ChristieChronicles.
Inquirer staff writer Suzette Parmley contributed to this article.