Thelen’s former employees are using a novel legal argument in an $18 million suit against five firms that hired many of Thelen’s partners, according to an opposition brief filed Friday.

The employees, represented by Los Angeles litigation boutique Blum Collins, argue the firms’ hiring of the partners amounted to purchasing a portion of Thelen’s business. Therefore, the firms are bound by the same obligations as an employer under the WARN Act. The defendant firms, meanwhile, argue that since there was no merger, they had no obligations to former Thelen staff.