A British judge will preside in Ireland for the first time since the nation’s independence 86 years ago, an Irish judge ruled Monday as an unprecedented lawsuit against IRA dissidents set more legal firsts.

The lawsuit by survivors of the 1998 car bombing in Omagh _ the bloodiest terror attack in Northern Ireland’s history with 29 dead _ is the first time that victims of terrorism in the British territory have sued members of the paramilitary group responsible.

The lawsuit opened in Belfast last month seeking $30 million in damages from five alleged dissidents directing the so-called Real IRA faction, which claimed responsibility for the atrocity.

Earlier this year, Irish legal authorities cleared the way for the lawsuit to collect evidence from Ireland’s police force in a Dublin courtroom. Never before has a British civil action been permitted inside a Republic of Ireland court.

Monday’s opening session in Dublin suffered immediate deadlock, however, as lawyers for the defendants demanded the right to challenge whether Irish police witnesses made any claims that would be inadmissible in a British court.

Irish District Court Judge Conal Gibbons initially ruled the defendants would have to raise those objections after returning to Northern Ireland. But the lawyers argued police witnesses would be free to make false, unfair or unsubstantiated claims against their clients that would be reported widely weeks before they could be challenged.

The Northern Ireland judge who is hearing most of the case in Belfast, Justice Declan Morgan, sat Monday in the public gallery and was not supposed to exercise any role in the Irish portion of the proceedings.

But in a surprise ruling, Gibbons said he would permit Morgan to hear arguments on the British admissibility of evidence collected in Dublin and deliver a judgment Tuesday. It wasn’t immediately clear whether Morgan would take Gibbons’ chair or the two would sit side by side.

The Omagh bombing was one of several in 1998 staged in Northern Ireland by dissidents trying to undermine public support for the Good Friday peace accord achieved that year.

Police insist they know who built and put the 500-pound bomb in Omagh, but lack forensic and witness evidence to secure criminal convictions. Civilians rarely testify against IRA figures because of the risk of ending up dead.

But the civil suit has a lower threshold of proof than criminal cases. The Omagh families were inspired partly by the successful U.S. civil action against O.J. Simpson finding him responsible for the 1994 murders of ex-wife Nicole Brown Simpson and her friend Ronald Goldman.