In the case of the International Transport Workers’ Federation and the Finnish Seamen’s Union v. Viking Line ABP and Oü Viking Line Eesti, the European Court of Justice (ECJ) has held that conditions laid down by trade unions for the registration of shipping vessels must not form an obstacle to freedom of establishment. The ECJ further held that trade unions’ right to participate in collective negotiations can be withheld in situations where workers will consequently benefit from higher levels of social protection.