The Lawyers and Conveyancers Disciplinary Tribunal has been asked to throw out a case against lawyer Donna Hall.
The case against Ms Hall has been taken by the Standards Committee of the Wellington District Law Society.
Ms Hall is accused of acting for more than one party in a land transaction in circumstances where she should not have.
In doing so she is accused of negligence or incompetence and bringing the law profession into disrepute.
Ms Hall's lawyer, Helen Cull QC, told the Tribunal the charge was laid under 2006 legislation, but the events complained of took place before that.
She said the Standards Committee now wishes to take action under the previous legislation, which would in effect mean Ms Hall faced a fresh charge.
Ms Cull said the Tribunal should not hear the case on that basis as it would be oppressive and unreasonable for it to do so.