Forward on lies, back on promises
But the various safeguards the Government is basing this argument on were also in the original version of the constitution - on which the government promised to hold a referendum.
In fact, the Labour party recognised this in The Labour Party manifesto 2005 (page 83 & 84)
"The EU now has 25 members and will continue to expand. The new Constitutional Treaty ensures the new Europe can work effectively, and that Britain keeps control of key national interests like foreign policy, taxation, social security and defence. The Treaty sets out what the EU can do and what it cannot".
The Government also tell us that we have never had a referendum on any other EU Treaty so we don't need one for the reform treaty. However, the Labour party has promised to hold a referendum with regards to a single element which was in the Maastricht Treaty which was signed in February 1992
The 2005 manifesto states:
"On the euro, we maintain our common-sense policy. The determining factor underpinning any government decision is the national economic interest and whether the case for joining is clear and unambiguous. The five economic tests must be met before any decision to join can be made. If the Government were to recommend joining, it would be put to a vote in Parliament and a referendum of the British people".
The 2005 manifesto also states at Page 110
"A referendum remains the right way to agree any change for Westminster".
No Parliament can bind its successor.