news.bbc.co.uk/1/hi/uk_politics/7319240.stm
The Lisbon Treaty would have no major impact on UK sovereignty according to the House of Lords constitution committee. It said it would have "no constitutional implications" for UK citizenship.
The Lords agree that Lisbon offers "greater clarity" over where the EU's powers stop and they conclude that "
the Lisbon treaty would make no alteration to the current relationship between the principles of primacy of European law and parliamentary sovereignty" and that "
The introduction of a provision explicitly confirming member states' right to withdraw from the EU underlines the point that the UK only remains bound by EU law as long as Parliament chooses to remain in the union."
The full report can be found
here