The Lisbon Treaty which came into force on 1 December 2009 alters institutional arrangements and the distribution of responsibilities within the European Union. Despite being an internal EU change it is certain to produce external effects.

Although neither the scale nor precise nature of these effects can yet be predicted clearly, this report, which was summarised by an issue of Commonwealth Trade Hot Topics offers a preliminary guide to the potential areas of change and an assessment of how these might impact upon Commonwealth developing countries in general (including least developed countries and small vulnerable economies) and on members of the ACP group in particular.