TRENTON, N.J. — Gov. Chris Christie and New Jersey’s biggest teacher’s union are again headed to a courtroom to settle differences after a judge ruled Wednesday the labor group must explain why it skipped meetings to help determine health insurance coverage and rates for public school teachers and retirees.

Judge Mary Jacobson granted the New Jersey attorney general’s request to require representatives from the New Jersey Education Association to explain why it missed at least two meetings this summer.

It’s the latest in a long-running fight between the Republican Christie administration and the NJEA over setting pensioners’ benefit rates. Christie wants to reduce benefits to save $250 million. The union is opposed.

New Jersey Education Association President Wendell Steinhauer, one of the three union representatives named in the case along with Kevin Kelleher and Carmen Gonzalez-Gannon, said the labor group will oppose the attorney general’s effort in court.

“We will pursue every legal opportunity to uphold state law and defend the legal rights of our members against the governor’s inappropriate actions.” he said.

Steinhauer said Christie is refusing to appoint an additional labor representative on the commission after a vacancy last year and is improperly trying to change retiree health benefits.

Attorney General Christopher Porrino said in court papers filed Tuesday that the union’s failure to attend meetings delayed efforts to set rates before open enrollment on Oct. 3.

“The NJEA-Commissioners’ deliberate absence is in violation of the law, the public trust, and their fiduciary duty,” Porrino said in the document.

Porrino says the School Employees’ Health Benefits Commission cannot vote on a proposal to save taxpayers $70 million because of the absence.

Last week, the union said the board could not do its job because the governor failed to fill a labor vacancy on the commission. Christie’s office deferred comment to Porrino.

The issue is coming to a head now because historically the commission meets in the summer to set rates and must have a rate chart ready for beneficiaries to review, according to the attorney general.

The union commissioners missed August meetings at which the panel was to consider switching its Medicare contract to a Medicare Advantage plan, for a savings of $70 million, with no change to coverage, Porrino wrote in the document.

Because the proposal could affect 2017 rates significantly it cannot first approve next year’s rates until the Medicare contract is addressed, according to Porrino.

Porrino is asking the court to require the union representatives to give times when they’re available to meet and if they do not, to compel them to attend a meeting on Sept. 16. If they continue to be absent, the administration is asking the court to allow the commission to vote on the question without the minimum five members typically required to be present.

The suit comes the same week that a separate state public benefits panel agreed to a Medicare Advantage contract change to save the state money. As a result, Christie freed up aid to towns that he had ordered frozen until the savings were identified

Jacobson’s ruling says the union representatives are to appear before her court in Trenton next Wednesday.

Christie and the union clashed in court over a 2011 law reached after a deal between the governor and unions that required the state to make regular annual pension payments in return for pensioners’ giving up cost-of-living adjustments. But the deal disintegrated after state revenues dipped below expectations and Christie shorted the pension payment.

NJEA and other public unions sued, but the state Supreme Court ultimately ruled in the governor’s favor.