The Treaty approved on October 19, 2007, in the capital of Portugal, comes in the context of the constitutional crisis provoked by the negative vote of the Dutch and French electorate in 2005, expressed on the occasion of the referendums organised in these states regarding the future European Constitution. The Treaty for the Union’s reformation fi rstly exploits the fl aws of the Constitution and secondly promotes the elements that appeared as stringent necessities for the future legal statute of the Union, now that the members has increased to 27 states. As the long-awaited reform treaty, also known as the Lisbon Treaty, may come into force as early as january 2010, this article is devoted to presenting and assessing the important institutional reforms brought by the treaty.