Which method have unions been the most successful in implementing in their dealings with MNCs?

Unions have been most successful in implementing collective bargaining as a method in their dealings with multinational corporations (MNCs). This approach allows unions to negotiate wages, benefits, and working conditions on behalf of workers, often resulting in binding agreements that enhance labor rights. Additionally, international solidarity and coordination among unions across borders have strengthened their bargaining power against MNCs. By leveraging these strategies, unions have been able to secure better outcomes for their members in a globalized economy.