"This is more than just solidarity with our colleagues in organized labor," said Denise Specht, president of teachers union Education Minnesota. "Our 86,000 members work with students during the flu season. They get sick. When they do, we want them treated by healthy nurses with easy access to quality health care themselves. The outcome of this dispute affects us all."

The teachers union asked those of their members who are in town for summer break to join nurses' picket lines. Education Minnesota flooded its Facebook and Twitter pages with bright protest photos accompanied with statements like "Educators will be there to stand up against Allina," and "Educators Support Nurses."

This was a problem for Allina. The hospital system tapped attorney Grant T. Collins of Felhaber Larson to write the teachers union a cease and desist letter on Tuesday.

"Please be advised that Allina Health’s hospitals are 'health care institutions' as defined by Section 2(14) of the National Labor Relations Act," Collins wrote. "As such, any picketing activities by a union must be preceded by a 10-day notice as required by Section 8(g) of the Act. The notice requirements of Section 8(g) are applicable even if the union does not represent, or seek to represent, health care employees."

Allina threatened to sue if the teachers didn't step away from the nurses immediately.

By law, unions have to give their employers 10 days notice before going on strike because bosses need a fair shot at finding replacements for them. In this case, nurses waited more than 10 days after voting to strike so that Allina could make arrangements for patients. Allina ended up hiring 1,400 temps.

In a rankled response to Allina, Education Minnesota's Specht told the lawyer that she would take extra cautions to make sure that the teachers union, as a labor organization, did not picket Allina hospitals. However, he could expect to see more teachers than ever joining the strike in their own capacity.

"We are happy you noticed the widespread support of nurses, but it is unfortunate that your efforts distract from the real work of settling a contract," Specht wrote. "When we notified other unions of your efforts to stop us in standing in solidarity with our brother and sister members of the Minnesota Nurses Association, they were just as appalled as we were. Educators across the state belong to more than 400 local unions that are not subject to the [National Labor Relations Act.] You will see more employees on their own time and more organizations not subject to the NLRA coming out to support nurses."

On Facebook, Education Minnesota reiterated their call for members to continue supporting nurses on strike. Teachers can wear whatever they want and carry signs saying whatever they want to write. There's just one new rule: don't imply Education Minnesota, the organization, is picketing against Allina. Instead, they're there to support their fellow unionized workers.