The law that covers police obtaining and using DNA in criminal investigations is too complicated says Law Commissioner Donna Buckingham.

She says DNA contains a huge amount of personal information and it is therefore important that the Criminal Investigations (Bodily Samples) Act 1995 is clear and protects people's rights.

Ms Buckingham was responding to the Court of Appeal decision R v Toki [2017] NZCA 513, released on 14 November 2017.

"In that case, Police used an incomplete template form that did not give Mr Toki full information about his rights when he voluntarily gave a DNA sample. The Court ruled that Mr Toki’s DNA evidence was inadmissible," the Law Commission statement says.

"Police now say 3677 people had their DNA taken unlawfully between September 2010 and August 2014 due to using the faulty form."

The Law Commission began a review of the Criminal Investigations (Bodily Samples) Act 1995 in July 2016 and plans to produce an issues paper in April 2018, with a full report by December 2018.