Boston-based Tufts Medical Center and the union representing roughly 1,200 of its nurses have seen several conflicts over the past year.
Below is a timeline of events between Tufts and the Massachusetts Nurses Association.
April 2016: The two parties begin contract negotiations.
June 2017: Tufts nurses reportedly reject a "final" contract offer from the hospital.
July 2017: Tufts nurses begin to strike after the union and Tufts fail to reach a last-minute agreement. The 24-hour strike ended around 7 a.m. July 13. However, Tufts barred striking nurses from their return to work until July 17 because the medical center needed to hire temporary replacement workers for a minimum of five days.
August 2017: Tufts and the MNA resume negotiations to try to reach a labor deal.
September 2017: Both sides agree to reschedule their next negotiating session so the union can further evaluate the hospital's latest contract offer.
October 2017: Tufts and the MNA continue negotiations.
November 2017: Tufts nurses hold their first picket since they went on strike in July.
November 2017: Rumors surface about a possible nurse strike on Christmas Day, although a strike authorization vote has not taken place. The next negotiating session is scheduled for Dec. 12.