A decision by the Chicago Teachers Union to refuse in-person work and instead continue teaching remotely because of health and safety concerns would constitute an “illegal strike” in the eyes of Chicago Public Schools officials, the district wrote in a letter to all teachers and staff on Thursday.

Though union leaders have been careful not to call their planned action a strike since teachers intend to keep working from home, CPS human resources chief Matt Lyons said the collective labor action of not returning to schools, as ordered by the district, “is a decision to strike.”

“This vote would cancel in-person learning for the tens of thousands of students who asked to return — and the thousands of pre-K and cluster students who are already learning safely in classrooms,” Lyons wrote.

“Pre-K and cluster program staff are expected to report to work on Monday — as they have done since Jan. 4 — and all K-8 staff without approved leaves of absence or accommodations are expected to report in person beginning Monday, Jan. 25. A collective failure to do so constitutes an illegal strike.”

The district is committed to continuing to negotiate daily, Lyons said, adding that “the union’s input has in many cases strengthened our reopening plan.”

The CTU, meanwhile, is adamant that its resolution for teachers to collectively refuse to return to classrooms — despite being in clear defiance of the district’s orders — wouldn’t be a strike.

“They’re not withholding their labor,” CTU attorney Thad Goodchild said in an interview. “They’re asking to work safely, and CPS is demanding that they work under unsafe conditions.”

The CTU’s 600-member House of Delegates approved a measure Wednesday that would see all union members refuse to work in-person until an agreement is reached with the district on health and safety protocols.

The union’s full membership is now voting through Saturday night on the following measure: “In response to serious unfair labor practices and the lack of a safe reopening agreement, do you authorize the CTU to conduct remote work only, starting on January 25?”

“In addition, in the event that CPS retaliates against or locks out members as a result, do you authorize a strike?”

It remains to be seen if CPS officials would lock out all teachers from remote work and withhold their pay as has been done with about 90 preschool and special education teachers and clinicians who have refused to report to their schools as ordered this month. A lockout would have the same effect as a strike — it would be impossible for classes to continue regardless of the venue. Union leadership is counting on putting the district in that bind to force its hand at the negotiating table.

If the full union agrees to the resolution and CPS responds by locking out teachers, the union has said it would call an official strike — and would be allowed to because of several alleged unfair labor practices: the failure to provide a safe workplace, the refusal to comply with an arbitrator’s ruling and retaliation against employees for protecting their safety, among others. Illinois educational labor officials have never ruled on whether a strike over an unfair labor practice is legal or not, Goodchild said, but there is national labor precedent that it is.

Goodchild also argued that the district’s order to reopen schools is currently being contested in labor court — the case is due for an administrative trial next week — and the CTU is simply refusing to comply with a directive it views as illegal.

Asked about CPS’ letter, CTU Vice President Stacy Davis Gates said at an afternoon news conference that the district has called “every collective action we’ve ever done” illegal, and “to be perfectly honest with you, we don’t think much of it.”

“For what it’s worth, our members didn’t vote on a strike. Our members voted to remain in remote learning to mitigate disaster.”

Goodchild would not say whether members who do report to schools on Monday would face discipline from the union as so-called “scabs” would for crossing a picket line during a strike.

“That’s not our focus, our focus is keeping everyone safe,” Goodchild said. “Our members are going to realize that by doing that they are undermining their own safety and the safety of their colleagues and the safety of their families. That’s the focus here. This isn’t about trying to threaten people with consequences.

“We’re in the middle of a pandemic. The consequences that we’re concerned about are the health and safety consequences posed by the pandemic and by CPS’ reckless mishandling of the question of how and when to safely resume in-person learning. … We are focused on acting as one union. Our union does that well. Our members are being put in just a horrible spot by the mayor and her team at CPS.”