KEY POINTS:
The Justice Minister says he expects strong public debate over the Criminal Investigations (Bodily Samples) Amendment Bill, which allows DNA to be taken from anyone the police "intend to charge" with an imprisonable offence. So there should be.
This legislation imposes a far lower threshold than the current law, which involves serious offences punishable by more than seven years' imprisonment. Equally, the taking and storage of DNA samples is under the spotlight internationally, following the European Court of Human Rights' swingeing criticism of British practice.
New Zealand's legislation echoes that of Britain in allowing the police to take samples without the safeguard of a judicial warrant or other independent approval. In that respect, it is out of step with most other comparable jurisdictions.
That point has been picked up by the Attorney-General, Chris Finlayson, who also says the legislation appears to be inconsistent with the "unreasonable search and seizure" provisions of the New Zealand Bill of Rights Act.
Such are the frictions when politicians strive to be tough on crime. The danger is that innocent citizens can be ensnared in a dragnet that becomes progressively wider.
There is, of course, good reason for the police to want to expand the use of DNA sampling. It is startlingly simple, and the time taken to identify suspects is dramatically shortened. Dangerous criminals can be removed from the streets far earlier. The Prime Minister, justifying the extension of the criteria, termed DNA the "modern-day fingerprint". That is not quite so. People's genetic fingerprints reveal more intimate details of their biological make-up.
It is also not right to say that people who are not liable to commit anything more serious than a speeding offence have nothing to fear. This implies utter faith in the use of DNA.
Yet even conventional DNA evidence is not foolproof. Britain's Home Office has conceded that in more than 50,000 instances between 2001 and 2007, DNA samples taken from the crime scene resulted in multiple matches. The evidence remains of use because most matches are quickly eliminated from inquiries.
But the bigger the database, the more serious the problem. And that forensic fallibility is exacerbated by the possibility of human error in DNA's collection and cataloguing. In this country, there has already been at least one example of a mismatch caused by the contamination of samples during processing.
As a tool, DNA depends on the quality of the database. This is of greater importance than the actual collection. Overseeing the database cannot, therefore, be left solely to the investigating authorities, as proposed by this legislation. An independent party must be employed as a statutory safeguard. Other significant issues will also have to be addressed. Samples should not be retained if, for example, people are not convicted or have volunteered their DNA.
Attention must also be paid to the safeguards recommended in the European Court of Human Rights' verdict.
There are undoubtedly strong reasons for the expanded use of DNA sampling. Equally, however, there is a strong case for ensuring that people's right to privacy is protected. Supporters of wider sampling will doubtless make light of this.
They will argue that if innocent people's rights are occasionally infringed in the crackdown against crime, that is a reasonable price to pay. Precisely the same people would normally rail against other examples of what they consider unnecessary state intrusion. A balance must be struck between the privacy of the individual and the public need. That must not entail undermining cherished liberties.