The Transatlantic Trade and Investment Partnership (TTIP) being negotiated between the European Commission and US government is aimed at boosting trade between the two economic powerhouses.

The Commission argues that the EU economy could benefit to the tune of €199bn a year and the Irish Government is firmly behind TTIP, despite staunch opposition across much of Europe.

One of the most controversial aspects of the proposed deal is the inclusion of an investment court system (ICS), which critics argue would give corporations the power to sue sovereign states in trade disputes.

In a potentially major blow to the Government and EU hopes for a deal, legal opinion seen by the Irish Examiner claims such a court system would require a referendum to be ratified.

Dublin-based senior counsel and former chairman of the Bar Council of England and Wales Matthias Kelly said the proposed investment court would “certainly infringe” upon the Irish Constitution in two areas and possibly three. In his opinion, the investment court system would:

Possibly infringe on Article 15.2.1 which vests sole power to make law in the Oireachtas;

Certainly infringe on Article 34.1 which vests the power to dispense justice in the Irish domestic courts;

Certainly infringe on Article 34.3.2 which makes the High Court and Appellate Courts above it the sole court in which a law may be questioned.

Sinn Féin MEP Matt Carthy called ICS the “greatest cause of concern” in TTIP talks and said the legal argument is “emphatic”.