High Quality Content by WIKIPEDIA articles! The Rosella or International Transport Workers Federation v Viking Line ABP IRLR 143 (C-438/05) is an EU law case, relevant to all labour law within the European Union, including UK labour law, which held that there is a positive right to strike. However, it also held that the right to strike must be exercised proportionately and in particular this right was subject to justification where it could infringe the right to freedom of establishment under the Treaty on the Functioning of the European Union article 49 (ex TEC article 43).