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A group of parents in Chicago has filed a lawsuit against the Chicago Teachers Union, claiming that school closures this week were the result of an "illegal strike."

The lawsuit, filed by the Liberty Justice Center on Thursday, seeks to get teachers back in the classroom.

"Because CTU members refused to teach under the conditions set forth by CPS — in-person instruction — CTU members are, by definition engaged in a strike," the lawsuit states.

The Chicago Public Schools closed classrooms beginning Wednesday as a result of a vote by the union to switch to a remote format, which the district refused to do.

A tweet by the union states that its members would return to in-person learning when either coronavirus cases "substantially subside" or when the city signs an agreement on "conditions of return."

The lawsuit also notes that the union received support from 73% of its members to withhold in-person teaching due to rising coronavirus cases as well as safety measures viewed as inadequate by the Chicago Public Schools.

That support level was "less than the three-fourths required to authorize a strike."

CHICAGO PUBLIC SCHOOLS CANCEL CLASSES FOR THIRD STRAIGHT DAY AS BATTLE WITH TEACHERS UNION CONTINUES

The Chicago Public Schools logo is seen Jan. 5, 2022, in Chicago. 

The Chicago Public Schools logo is seen Jan. 5, 2022, in Chicago.  (Getty Images)

Lawyers with the Liberty Justice Center were asking for an emergency hearing where a judge could order teachers back into the classroom.

Mental health toll

The decision by Chicago Teachers Union members not to show up to work is taking a toll on students' mental health, Ammie Kessem, a parent of a student within the Chicago Public Schools, who's also the 41st Ward Republican committeeman in Chicago, told Fox News Digital. 

"[Students] were just starting to get things back to normal. And now all of a sudden, they have the rug ripped out right from under them," Kessem said.

Kessem noted that teachers have various resources to keep themselves safe and there should be no work stoppage, and said she joined the lawsuit to get students back in school.

Chicago Mayor Lori Lightfoot speaks during a Jan. 4 news conference.

Chicago Mayor Lori Lightfoot speaks during a Jan. 4 news conference. (Facebook/ Chicago Public Schools)

"I'm a first responder. I have to be to work. And the bottom line is that these kids need to be in school. It's the safest place for them," Kessem said.

CHICAGO OFFERS MEALS, 'SAFE HAVEN SITES' FOR CHILDREN WHILE SCHOOLS UNEXPECTEDLY CLOSE

An attorney at the Liberty Justice Center claimed in a statement that the teachers union was violating its collective bargaining agreement with the Chicago Public Schools.

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Chicago Teachers Union President Jesse Sharkey speaks outside Peirce Elementary School on the first day of a strike by the union, Oct. 17, 2019. (Agence France-Presse) 

Chicago Teachers Union President Jesse Sharkey speaks outside Peirce Elementary School on the first day of a strike by the union, Oct. 17, 2019. (Agence France-Presse) 

"CTU’s resolution calling members to not show up for work in-person is a strike regardless of what CTU calls it and violates both the collective bargaining agreement with CPS and Illinois law," said Jeffrey Schwab, senior attorney at the Liberty Justice Center. "CTU cannot unilaterally decide what actions should be taken to keep public schools safe, completely silencing parents’ input about what is best for the health, safety, and well-being of their children."