The pact signed by 25 European countries to combat the eurozone crisis will do "little" and is "politically impossible to enforce", according to a parliamentary committee.
A report by the Commons European Scrutiny Committee said "The Stability, Coordination and Governance" (SCG) Treaty would only serve to provide "some comfort to international markets". It warned that, while undesirable, a breakdown in the financial system "clearly remains possible".
The committee urged the UK Government to view the treaty as unlawful because it does not enjoy unanimous support of all 27 EU members, as required by EU treaties.
"The approach taken to proceed with the fiscal compact raises a fundamental question about the application of the rule of law within the EU. The SCG Treaty would have been an EU treaty but for the veto.
"However, the EU institutions and the governments of the 25 Member States who have signed the Treaty, have embarked on a dangerous precedent in seeking to attain their political objectives irrespective of the rule of law in the EU," the committee said.
The Committee concluded that Cameron's veto was justified because of "the very real concerns about a breach of EU law, even if this was not the reason given exclusively for the use of the veto in the first place."
The committee said "serious questions" were raised by Europe Minister David Lidington when he was questioned by them. Lidington avoided discussing whether the treaty was illegal, claiming it would be "taking it a step further". His explanation was dismissed as having "no contextual basis" and "surprising".
Committee Chairman Bill Cash attacked the government"s "reticence" in its dealings with its EU neighbours, saying:
“Politically and legally, it is profoundly unwise for the Government to suggest taking action, and then not to explain how it intends to carry it through, or what concessions are now being sought and achieved.
“The approach to this Treaty provides further and ever more disturbing evidence of the European Union, in the context of increasingly coercive attitudes by Germany and France and the European establishment in pursuit of further and deeper political and legal integration, dangerously ignoring its own precepts for political ends.
"This is despite France and Germany’s own original failure over the Stability and Growth Pact. The Government must clearly state as soon as possible what action it now intends to take on the Treaty”.
Mats Persson, Director of Open Europe, told the Huffington Post UK that the fiscal compact was "legally dubious".
He disagreed with Bill Cash, saying that ""It is somewhat wise for the government not to reveal its hand. The UK would use the avenue of a legal challenge as a deterrent but the UK does not want to be seen as deliberately wrecking the EU treaty. The Treaty is, although legally unsound, is held together by that nervousness."
A timeline of the 2011-2012 Eurozone Crisis: