Labor was forced to abandon its promised mandatory internet filter because it would never have worked and would not have got through parliament, opposition communications spokesman Malcolm Turnbull says.
Communications Minister Stephen Conroy has abandoned the proposed filter five years after it was promised by Labor, following an outcry from civil libertarians and technology businesses.
Senator Conroy had not reinvented himself as a libertarian, "he's just been obliged to recognise reality", Mr Turnbull said.
"It was always a bad idea," he told The Australian.
"It would never have been effective. It would have just given parents a false sense of security. There is no substitute for parents taking responsibility for their children.
"It's an overdue acknowledgment that they don't have the numbers in either house to get their legislation through."
The government will instead require internet service providers to block child abuse material online, using existing powers under the Telecommunications Act.
"We've actually reached agreement with the industry to block child pornography and we think that is a significant step forward," Senator Conroy told ABC radio.
He said the decision followed a 2010 review of the policy taken to the 2007 election by Kevin Rudd.
Senator Conroy said the policy had been re-examined.
"Well the review took place, started in 2010 and has been completed now and we've accepted the recommendation. I think that's a very thorough process we've gone through.
"We've been negotiating with the telecommunications companies and we think this is a very good outcome."
Mr Turnbull said ISPs had been blocking such sites "for years".
"What he has announced today is standard practice," Mr Turnbull said.