Assaults in Sydney have not decreased by as much as Premier Mike Baird claims, the state's leading crime number cruncher has said, adding that violence was already in decline before lockout laws were introduced.

Key points: Assaults in Sydney have not dropped as rapidly as Mike Baird said, top statistician says

Assaults in Sydney have not dropped as rapidly as Mike Baird said, top statistician says Don Weatherburn says assaults down by 40 per cent in Kings Cross and 20 per cent in the CBD

Don Weatherburn says assaults down by 40 per cent in Kings Cross and 20 per cent in the CBD Mr Baird says assaults were down 60 per cent in the the Cross, and 42.2 per cent in the city

Mr Baird says assaults were down 60 per cent in the the Cross, and 42.2 per cent in the city Decline in violence began before lockout laws, Weatherburn says

Don Weatherburn, director of the New South Wales Bureau of Crime Statistics and Research told 702 ABC Sydney's Mornings that the lockout laws had reduced assaults in Kings Cross by 40 per cent and in the central CBD entertainment district by 20 per cent.

In Mr Baird's Facebook post yesterday, which has since received more than 11,000 comments, the Premier said alcohol-related violence had dropped by 60 per cent in Kings Cross and 42.2 per cent in Sydney's CBD.

But Dr Weatherburn said he suspected the Premier was comparing the situation before the lockout laws and the situation after.

"The problem with that is assaults have been coming down in NSW since 2008, so you had this pre-existing downward trend," Dr Weatherburn said.

"What the lockout laws did was accelerate the existing downward trend, so it fell even faster than before."

He said the number of people heading into Kings Cross and the amount of alcohol consumed had dropped remarkably.

"The people that used to go to Kings Cross at one or three o'clock in the morning have simply scattered to wherever they came from, and they're not bumping into the people they would have had a fight with.

"Kings Cross tended to attract people who liked to drink a lot and liked to fight when they drank.

"Now they don't run into people like themselves as much."

In his post, Mr Baird said some people were criticising the state's lockout laws, introduced in 2014, because they were killing the city's nightlife.

"The main complaints seem to be that you can't drink till dawn any more and you can't impulse-buy a bottle of white after 10pm," Mr Baird said.

"Some say this makes us an international embarrassment.

Premier Mike Baird says the state's lockout laws have made Sydney safer. ( AAP: Nikki Short )

"Except, assaults are down by 42.2 per cent. And there's nothing embarrassing about that.

"We introduced the laws to curb violence and to eliminate drinking ghettos by redistributing the nightlife across the city, making the whole city more vibrant."

Mr Baird said that anecdotal evidence already suggested that the city was becoming safer and the number of small bars in Sydney had doubled in the time since the laws were introduced.

His Facebook post came as Sydney's Lord Mayor Clover Moore weighed in on a debate about whether police were too heavy handed when dealing with an inner-city restaurant at the weekend.

NSW Police questioned the owners of 10 William St Paddington, after officers helped a drunk woman from the gutter outside the restaurant into a taxi.

Restaurant owner Giovanni Paradiso said police accused the restaurant of "promoting unsavoury antisocial behaviour" because a blackboard wine list was too close to the front of the restaurant.

Police defended their comments, explaining that the blackboard did not mention food, suggesting the venue was operating more as a wine bar than a restaurant.

Last week, an essay attacking the laws written by Australian entrepreneur Matt Barrie and published online drew more than 200,000 views in under 24 hours.

In the essay, Mr Barrie spoke of politicians on a "moralistic crusade" turning Sydney into an "international joke".

No evidence assaults moved to Newtown

When asked whether there was any evidence that violence had shifted from Kings Cross to outer suburbs, Dr Weatherburn said crime figures did not support that idea either.

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"We don't see any evidence of that. In the early part of the evaluation we saw a brief increase around Darling Harbour, near the casino.

"People have talked endlessly of an increase of assaults in Newtown; we don't see any evidence whatsoever of that.

"I have a suspicion that what people are getting confused about is the usual seasonal increase in violence in summer months."

He said there was no increase in violence in suburbs such as Bondi, Bondi Junction or Coogee.

Dr Weatherburn said there was no evidence of a "displacement effect" increasing domestic violence since the lockout laws were introduced.

"The number of domestic violence incidents have not changed, but you have to remember that only a third of incidents are reported to police."

Hospital frontline staff and victims support Government

Director of trauma at St Vincent's Hospital Associate Professor Tony Grabs said the lockout laws had had a profound impact on the number of people being injured by alcohol-fuelled violence.

"It has been a breath of fresh air for this hospital," he said

"What we see now is the number of people coming in with associated head injuries and alcohol-related violence has dropped dramatically."

Former security guard and one-punch victim Fady "Freddie" Taiba also supports the laws and has urged the Government not to concede to critics.

"I don't believe we should listen to these people saying 'this is not a fun place to be'," he said.

Mr Taiba said the value of life should not be compared to the loss of the so-called night time economy.

"All they're thinking about is money … No amount of money of gold in the world can replace the death of someone," he said.