The dispute between Chicago’s school district and teachers union over pay for veteran teachers has advanced beyond the two partners, with an investigation by a state labor relations board now underway, according to union officials.

In the one major unresolved issue from the strike, the Chicago Teachers Union and Chicago Public Schools still haven’t agreed on whether to parcel out $25 million in promised raises for veteran educators primarily as bonuses, or to add the money to teachers’ base pay. 

The union filed an unfair labor practice complaint on the issue with the Illinois Education Labor Relations Board in December. 

Now, an investigator has been assigned to gather evidence from both sides. The investigator will issue a ruling and help facilitate a settlement. If either side disagrees with the ruling, it can appeal the decision and force a hearing. 

The labor board’s ruling is legally binding in that it is supported by a court order, but don’t expect it to immediately clear up the issue, labor experts said. 

“The ruling will be important in providing leverage to the parties to work it out,” said Bob Bruno, professor of labor at the University of Illinois at Urbana-Champaign. 

Steven Ashby, a labor professor at the University of Illinois at Urbana-Champaign who wrote a book with Bruno on the Chicago Teachers Union, said he would be “shocked if both sides don’t accept the labor board’s decision.” 

Yet, even if the labor board backs one side over the other after months of deliberation, the district and union will still have to work together to negotiate a solution. 

The union brought the issue up most recently at Wednesday’s Chicago school board meeting, where union Financial Secretary Maria Moreno asked board members to work with the district and resolve the dispute. 

“Let’s not get bogged down so soon after the ink has barely dried on our new collective bargaining agreement,” she said. “As soon as CTU members voted to ratify the agreement, the district broke our deal and demanded that most of the $25 million be paid in a one-time lump sum.” 

Days earlier, a court dismissed a union lawsuit alleging the district discriminated against black teachers during a series of layoffs in 2011. 

Now, the union is gathering material for the investigator, attorney Josiah Groff said. 

The district, meanwhile, said that by Tuesday night they had not yet been contacted by any state labor board investigators. 

They are willing to pay out the funds, district spokesman Michael Passman said, but not primarily as additions to base pay. “As part of the district’s historic agreement with the Chicago Teachers Union, CPS committed to providing $25 million in additional pay over the next five years,” he said. “CPS stands by this commitment and is ready to begin paying out these funds as soon as an agreement is reached.” 

The Illinois labor relations board did not respond to an inquiry about the status of the case.