Emanuel announced Sunday that he has instructed city lawyers to file an injunction in circuit court to end the strike that would return the city's 350,000 children to the classroom.
The dispute looked as if it was drawing to a close over the weekend with union leaders asking that the strike be suspended. However, a majority of the approximately 800 union delegates defied the union leadership, sending the strike into its second week.
The strike, which began Sept. 10, is Chicago's first in 25 years and involves an estimated 29,000 public school teachers and support staff.
"I will not stand by while the children of Chicago are played as pawns in an internal dispute within a union," Emanuel said, in a statement. "This was a strike of choice and is now a delay of choice that is wrong for our children. Every day our kids are kept out of school is one more day we fail in our mission: to ensure that every child in every community has an education that matches their potential."
He added that continued strike is illegal because "it is over issues that are deemed by state law to be non-strikable, and it endangers the health and safety of our children."
Teachers Union President Karen Lewis has said the decision to strike was a difficult decision one to make.
"But this is the only way to get the Board's attention and show them we are serious about getting a fair contract which will give our students the resources they deserve," Lewis said.
The Chicago Teachers Union said it has been in contract negotiations with the Chicago Public Schools since last November. It also said the teachers have been without a contract since this June, when its five-year agreement with the district expired. A new agreement was not in place.
The Associated Press reported that teachers are now uncomfortable about approving a contract they have only seen in parts.
The union is set to meet again Tuesday.