But data gathered by the City of Sydney suggests that may be a result of fewer people partying in Kings Cross and the CBD, as evidence by footpath congestion down 84 per cent in some areas.

NSW Police Assistant Commissioner Michael Fuller fronted a NSW parliamentary inquiry on Wednesday into reducing alcohol and drug violence and said intelligence from local officers showed there was a feeling "on the ground that there is a positive move towards a safer environment".

Mr Fuller said, in the six months since the laws came into effect, there had been two recorded incidents of assault causing grievous bodily harm. In the same six month period last year – from the end of February to the end of August – there had been 22.

Police had also issued about 350 banning orders for Kings Cross, "the majority of which have been short term but there are a few long term". Banning orders allowed police to apply to have anyone convicted of a serious alcohol-related offence banished from the Kings Cross precinct for up to a year.

"The police also feel there's been encouraging signs in the reduction of intoxication," he told the inquiry.

The lock-out laws came into effect on February 24 to combat alcohol-related violence after the one-punch deaths of Thomas Kelly and Daniel Christie. Licensed premises in Sydney's CBD and Kings Cross are required to lock out patrons from 1:30am and stop serving alcohol at 3am.

Mr Fuller acknowledged there were now fewer people on the streets at night, which would contribute to the drop in assaults. Research conducted by the City of Sydney over six Saturday nights in March and April found footpath congestion was down 84 per cent on Darlinghurst Road and 78 per cent on Bayswater Road, compared with levels in December 2012.

The council's acting manager of city business and safety Kate O'Connor told the inquiry CCTV footage and observations by council officers showed there were also fewer people on the streets and fewer incidents in the CBD.

In its submission to the inquiry, the City of Sydney raised concerns that some businesses had closed or were struggling to survive since the laws were introduced. Ms O'Connor said a "more nuanced approach" should be considered, particularly with regard to live music venues.

The council reiterated its call for the measures to be reviewed after one year instead of two.

Pubs and clubs argued the laws would move drunken violence to areas outside the lock-out zone, such as Newtown, Pyrmont and Paddington.

Mr Fuller said police were reporting slightly larger crowds in those areas but no increase in violence. Staff from St Vincent's Hospital told the inquiry there had been a significant reduction in alcohol-related presentations at the hospital and Royal Prince Alfred, near Newtown, had also had a small reduction.

Earlier, the director of the NSW Bureau of Crime Statistics and Research Don Weatherburn said his organisation would be examining if "displacement" of alcohol-related violence was an issue. The bureau would release its latest crime statistics on Thursday, but Dr Weatherburn said it was too soon to evaluate the laws' success because the assault rate always dropped after its peak in January.

"It is too early to judge, we really need more than four months of data," he said.

The director of liquor and policing at the Australian Hotels Association NSW John Green told the inquiry the government had "moved too quickly" and imposed too many regulations at once, so it was impossible to tell which ones were effective. He was critical of the decision to ban takeaway liquor sales after 10pm, saying pubs and farmers in country areas were the "unintended victims" of the policy.

"Regional NSW is really suffering and can't see the rationale for all this," Mr Green said.

Ralph Kelly, Thomas Kelly's father, also addressed the inquiry and urged a review of the "offensive", "cold" and "sterile" judicial system that he said was "in the favour of the offender". He sympathised with businesses that were doing it tough but said it was more important to reduce violence.

"I understand that shopkeepers and nightclubs are going through pain, but we cannot let this carnage continue," he told the inquiry.