The Court of Appeal has begun hearing a prominent republican's attempt to have his conviction for tax evasion set aside.

Thomas ‘Slab’ Murphy, of Ballybinaby, Hackballscross, Co. Louth is also appealing the 18-month sentence handed down earlier this year.

Senior Counsel John Kearney, who is representing Thomas Murphy, said the real dispute revolves around whether the “guiding principles” were properly applied in the original case - or applied at all.

Following a 32-day trial before the non-jury Special Criminal Court, Murphy was found guilty of not filing tax returns for his farm between 1996 and 2004.

He maintained he had been the victim of identity theft and that it was his brother who ran the farm.

Today, Mr Kearney criticised some of the evidence relied on by the lower court - particularly the testimony of retired Department of Agriculture worker Pat Rafferty.

Mr Rafferty said Murphy had signed a form in his presence, which suggested he was in charge.

The barrister said this was a “fatal finding of fact” based on a misunderstanding and couldn’t be further from the truth.

He said there was no way of knowing whether the alleged misunderstanding had infected the rest of the evidence.

The hearing is expected to take at least three days.