The introduction of fixed fees for lawyers representing clients who have legal aid is being challenged in the High Court in Wellington.
The Criminal Bar Association wants the Government's new legal aid payment scheme declared unlawful.
Under the new scheme, which came into effect in March this year, lawyers are paid a set fee based on the seriousness of their client's offending, rather than the amount of work performed on the case.
Previously an hourly rate was paid.
The judicial review hearing is set down for three days.