A fresh appeal launched by Ian Bailey against his extradition order to France in connection with the killing of a French film maker has got under way.
The Supreme Court heard arguments from British-born Bailey's senior counsel Garrett Simons, who claimed that the French legal system has no right to exercise authority over the case in Ireland.
He argued that France should not be able to extradite a citizen from a third country in a case where, if reversed, Ireland could not do the same in France.
Bailey is wanted for questioning by an investigating judge in France in connection with the murder of Sophie Toscan du Plantier in Schull, Co Cork in 1996.
He has continued to deny any involvement in the 39-year-old's death and has never been prosecuted.
The 54-year-old former journalist is a British citizen. His counsel Mr Simons argued that in the hypothetical case of a British citizen allegedly murdering an Irish citizen in France, Ireland would not have the power to extradite him.
He said the appeal was based on the idea of reciprocity, as defined under section 44 of the of the European Arrest Warrant Act 2003.
"Section 44 sets out and recognises the principle of reciprocity where a state is not required to extradite somebody to another state in circumstances where the reverse situation where the reverse state would not have a right to prosecute," said Mr Simons.
But senior counsel for the state Robert Barron argued that the principal of reciprocity is not part of the framework of the Act in question.
Mr Simons added that Irish law is centred on the citizenship of the accused, while French law focusses on the citizenship of the victim. He said there was no reciprocity between the states and the accused cannot be extradited.