asked Her Majesty's Government:

Whether the European Union can require internal constitutional changes by applicant states, in particular for federal countries such as Bosnia and Herzegovina; whether there is discretion in such matters; and whether they are the responsibility of the Commission or the Council of Ministers, or both. [HL3107]

In order to join the EU, candidates must meet the Copenhagen criteria, including political and economic requirements, as well as adopting the EU legislation (the EU acquis). This may involve far-reaching legislative reforms.

For a pre-candidate country such as Bosnia-Herzegovina, the European Commission proposes an annual assessment of progress and reform priorities. These assessments may sometimes highlight the need for constitutional changes. The Commission manages and supports pre-accession preparations. The member states must unanimously agree each stage of the accession process, for example the signature of a stabilisation and association agreement.