By RTÉ Europe Editor Sean Whelan

Can Ireland veto a trade deal after the Lisbon Treaty is signed?

This issue has become hugely controversial in the campaign - thanks to the Irish Farmers Association (IFA) and Libertas – though both take different views on the existence of a veto.

Libertas says there is no power to veto a trade deal, and demands the Government show where in the Lisbon Treaty such a veto exists. It says even under existing treaties, there is no veto right.

The IFA says there is a veto power and has called on the Government to use it. It cites the French (who have ratified Lisbon) as threatening to use the veto in the current WTO trade talks. If the veto doesn’t exist, how can the French be threatening to use it?

The Government insists there is a veto right, but has not pointed out in detail, or in writing, how it works.

Their problem is twofold. Firstly there has been a watering down of veto rights between the Nice Treaty and the Lisbon Treaty. Secondly, because of the structure of the Lisbon Treaty, the veto powers are dispersed over a number of parts of the Treaty, rather than grouped together in article 133 of the current treaties.

The European Commission has set out how a veto in WTO talks works in a detailed note.

In effect, if a trade deal only concerns physical goods, such as beef, then there is no veto right.

However, if it includes transport services, some aspects of Intellectual Property law, such as enforcement of protection measures, audiovisual services or any measure for which unanimity is required in EU decision making (notably tax) – then the whole package becomes a unanimity measure, therefore a veto exists.

The commission call this the 'Pastis Principle', after the French alcoholic drink (a close relative of Pernod) which changes from being clear to cloudy white if a drop of water is added.

So with trade, any deal that includes any element for which unanimity is required turns from QMV into unanimity for the whole package, because WTO deals are assessed as a total package.

Libertas says it has legal advice on the absence of the veto, but has refused to disclose this advice to RTÉ News. It also says a number of MEPs back its view, but will not say who these elected representatives are.

Libertas has published an e-mail it received from the Europe Direct helpline (a commission run info service for the public).  The help line note says no country has a veto on trade deals under article 188.

This is correct but not complete, because of the 'pastis principle'.  Even the Commission's own helpline apparently can't follow this part of the treaty.  (Also the e-mail to Libertas contains a disclaimer at the bottom stating that the contents of the e-mail are not a legally binding opinion).

The Irish government, the French government (apparently), the European commission and the IFA all say there is a veto right.

Danish Euro-sceptic Jens Peter Bonde told me there is a veto right in the way the Commission and Irish government say, but stresses there is no veto right for trade deals involving only trade in goods. This appears to be the case in the current treaties also.

In short, the balance of evidence strongly suggests there is a veto right over WTO-type complex trade deals, as described above – but without expert knowledge of the treaty it is virtually impossible to find in black and white.