Trade unions cannot force the employer into everlasting solutions or block any changes to them.
Work rules (a.k.a employee handbook) are a key employment policy document for employers, especially those with union organisations in their companies. But the unions are often totally recalcitrant, deliberately trying to prevent any changes in the rules.
For many years the Supreme Court’s judgment of 21 March 2001 in case no. I PKN 320/00 has been one of the most important references defining the role of the unions in the work rules negotiation process. This was a very unfortunate judgment. It practically imposed a principle that work rules could be changed only with the consent of the unions. Furthermore, the court interpreted the Labour Code in such a way as to require the employer to agree change negotiation dates with the unions.