The labor dispute between Mayo Clinic Health System Albert Lea and the Service Employees International Union (SEIU) continues, after union officials say the National Relations Labor Board found merit to the charges that Mayo illegally locked out employees over Christmas.

Union workers participated in a one-day strike over contract negotiations in December, and following it employees were locked out for a week.

Mayo Clinic spokesperson Ginger Plumbo said at the time that the hospital had no other choice because the institution needed to maintain safe patient care, and that they warned ahead of the strike that the law required replacement workers to be hired for an entire week.

SEIU has filed new charges accusing Mayo of retaliation against Albert Lea workers who went on strike, saying that Mayo management has been interfering with and discouraging members from discussing negotiations and organizing union meetings.