Related: Women The European Union Bill 2004–2005 (Bill 45) was a bill of the United Kingdom Parliament which proposed to ratify the European Constitution and to incorporate it into the domestic law of the United Kingdom and to amend the European Communities Act 1972 to include it in the list of Treaties and hold a referendum throughout the United Kingdom and Gibraltar on whether to approve the proposed Constitution which would be overseen by the Electoral Commission.

The bill was first introduced during the parliamentary session of 2004/2005 and received a second reading.

The bill was reintroduced in the new parliament and the 2005/2006 session; however, it was withdrawn after its first reading by Jack Straw on 6 June 2005 following "no" votes in referendums that were held on ratifying the European Constitution in France and in the Netherlands.

[2] The bill gave the question to appear on ballot papers: Should the United Kingdom approve the Treaty establishing a Constitution for the European Union?

and in Welsh: A ddylai’r Deyrnas Unedig dderbyn y Cytuniad a fyddai’n sefydlu Cyfansoddiad i’r Undeb Ewropeaidd?