contrary to previous thinking, one effect of Article 11 of the European Convention on Human Rights (right to form and to join a trade union) is that the right to bargain collectively should nowadays be regarded as "one of the essential elements inherent in the right to form trade unions".
For relevant general notes see Definitions and interpretation/collective bargaining and/or Trade union matters/consultation with/collective bargaining and/or Strikes/a general note and/or Human Rights/a general note .