Anthony John Hill, 60, originally from Sheffield in England, was arrested in Kells, Co Meath, this morning of foot of a European arrest warrant.
Mr Hill faces one charge of attempting to pervert the course of justice during the trial.
It is understood he is accused of sending DVDs relating to a conspiracy theory on the London bombings to the trial judge and members of the jury.
He was remanded in custody until 18 February.
