"That is a very significant step Parliament is being asked to make."
Dr Butler acknowledged serious crimes were committed by people on bail. But he felt the evidence did not justify the amendment.
Ministry of Justice figures showed that out of 123 people bailed while on murder charges over four years, 14 committed an offence while on bail, and seven of these committed an imprisonable offence. "So we're talking a very small number of people who abuse the bail system," Dr Butler said.
Human Rights Commission chief commissioner David Rutherford said public demand for bail reform seemed to be based on high-profile cases, but there was less than one serious crime committed by a person on bail each year.
"Each one of these is one too many, but changes in practice and policy might be more effective than proposed changes in the law," he said.
The introduction of the bill coincided with the launch of a community movement called "Christie's Law", which aimed to tighten bail laws. The campaign was founded by the Sensible Sentencing Trust and the parents of slain North Shore teenager Christie Marceau. Akshay Chand, 19, has been charged with murdering her while he was on bail.
Yesterday, some submitters recommended greater scrutiny of judges' decisions, in the form of a case-by-case review system similar to the Health and Disability Commissioner's review of medical errors.
The Law Society said it was incredibly complex to predict which offenders would reoffend while on bail. Therefore the discretion of who should get bail was best left to a judge, rather than a law change.
Dr Butler: "There is no foolproof way of identifying who those people are that are likely to commit crimes while on bail.
"At the moment we give judges the ability to make fact-sensitive assessments which do allow for that sensitivity and focus.
"They don't always get it right, that's true, but will this bill really assist?"
BAIL AMENDMENT BILL
* Reverses burden of proof for serious offences in bail cases.
* Broadens list of offences in which defendant will have to demonstrate they will not be a threat if released.
* 17- to 19-year-old repeat offenders face adult test to get bail.
* Police can pick up bail skippers and take them home, and arrest people who repeatedly breach bail without a warrant.
* Allows district courts to deal with serious offenders in bail cases.