Convicted killer Helen Milner has lost her bid to challenge her murder conviction in the Supreme Court.
But the court said another application for an appeal could be made if further investigation reveals her husband, Phil Nisbet, may not have died from a drug overdose.
Milner was sentenced to life in prison for killing Mr Nisbet with an overdose in 2009 and making the death appear to be suicide.
She appealed against her convictions for murder and attempted murder on the grounds the Crown had not proven the drug had could have been administered without Mr Nisbet's knowledge.
The drug promethazine hydrochloride, or Phernergan, tastes bitter in lethal quantities.