NEW ''one-punch'' laws are proving difficult to implement and the government has been forced to delay the introduction of mandatory sentencing for serious assaults until the end of next month.
Premier Barry O'Farrell said he would introduce, on Thursday, minimum mandatory sentences for assault causing death, as announced last week, but he would have to delay legislation covering serious assaults.
The proposed mandatory sentencing laws would apply to violence involving alcohol and drugs as part of a crackdown on one-punch assaults that have killed some victims and left others with serious brain damage.
''When we come back in the last week of February, in three weeks' time, we'll deal with the minimum mandatory sentences for serious violent assaults,'' Mr O'Farrell said.
Asked why there would be a delay, Mr O'Farrell said on Tuesday that ''some of these things are easy to introduce, others will take some time''.
''What I said last Tuesday is that Parliament would come back depending on how the drafting was going,'' he said.
''What we're determined to do is ensure that we put in place laws that are effective.''
NSW Bar Association president Phillip Boulten said the proposed legislation would be difficult to implement.
''It is clear the government is finding it difficult to translate this announcement of the Premier's into legislation and that is not surprising,'' he said.
''It will be difficult for the government to identify an appropriate way to identify whether someone is affected by alcohol or drugs at the time of the offence.''
Mr Boulten said drugs such as cannabis could remain in the body and be detected within a month of being taken. The question of how alcohol consumption would be measured and at what point a person would be deemed to be affected by alcohol, was also problematic.
Mr O'Farrell said section 10 bonds, which allow for the dismissal of charges against someone found guilty of an offence, would not be available to magistrates under the proposed one-punch laws.
He also rejected concerns that the legislation would disproportionately affect Aborigines.
''I don't believe that's the case,'' he said. ''I do know the legal profession is campaigning against it. I'm not surprised that there will be claims made. But this is a measured response to a very serious problem, not just in the Sydney CBD but across the state.''
According to the NSW Bar Association, Aboriginal offenders were grossly over-represented in jails when mandatory sentences were introduced in the Northern Territory and Western Australia.
It said the Australian Bureau of Statistics had reported a 58.6 per cent increase in the indigenous incarceration rate between 2000 and 2010. The non-indigenous rate increased only slightly.