A top lawyer is confident plans will be put in place to stop the sentencing of the Christchurch mosque gunman becoming a circus

Brenton Tarrant sacked his lawyers - after earlier pleading guilty to killing 51 people and injuring another 40 in the mosque attacks last March.

His decision to defend himself means he'll now be able to speak in court.

Marie Dyhrberg QC says the public will feel that means Tarrant can do and say whatever he pleases - and spout his ideology.

But she says in reality, that's not going to be allowed to happen.

Marie Dyhrberg says the judge will prepare, and work with court staff and security to tightly control the sentencing.