A bid to have the £15m Omagh bomb compensation case dismissed has been rejected in the Court of Appeal.
Twenty-nine people died in Omagh bombing in August 1998
Two defendants - Colm Murphy and Seamus Daly - claimed alleged irregularities by solicitors representing the families meant it should be thrown out.
The 1998 Real IRA bomb killed 29, including a woman pregnant with twins.
Earlier this year Mr Justice Morgan dismissed an application by Murphy and Daly to strike out the claim and Friday's decision upheld that.
The Lord Chief Justice, Sir Brian Kerr, said one of the grounds advanced on behalf of Murphy and Daly, two of the five defendants, was that the writ did not comply with court rules because the London legal firm of H20 had no business address within Northern Ireland.
Sir Brian said a Belfast firm of solicitors had agreed to allow their offices to be used as an address for service but were unwilling to be named as agents of the plaintiffs' solicitors for security reasons.
He said that if a local address was necessary, "we consider that the circumstances of the case justify our refusal to set aside the proceedings on account of that irregularity".
Sir Brian added: "Because of the nature of the case the plaintiffs have found it impossible to engage solicitors in Northern Ireland.
"To require the present solicitors to establish business premises here simply to secure technical compliance with the rules would not be in the interests of justice."