Catherine Nevin's conviction for murdering her husband, Tom, can be used in a case taken by his family to try to stop her inheriting his estate.
The decision by the Court of Appeal means a full hearing of the High Court action by Mr Nevin's brother and sister aimed at disinheriting their sister-in-law can go ahead.
They are also claiming damages against her for wrongful death.
Catherine Nevin was jailed in 2000 for the murder of her husband at their pub, Jack White's Inn, near Brittas Bay in Co Wicklow on 19 March 1996.
Her appeals against her conviction failed, as did an application to have it declared a miscarriage of justice.
Tom Nevin did not leave a will.
His assets included the pub, jointly owned with his wife, two Dublin properties, an insurance policy of IR£78,000 and IR£197,000 in cash.
Ms Nevin sold the pub in 1997 for IR£620,000.
Mr Nevin's brother Patrick and sister, Margaret Lavelle, brought a preliminary application to the High Court to admit evidence of Ms Nevin's murder conviction as part of their disinheritance proceedings.
The High Court found in their favour and that decision has now been upheld by the Appeal Court.
Ms Nevin claims she was entitled to her late husband's assets, or part of them.
She says she is not guilty of his murder.