The government believes the laws, which allow about 85 security and policing agencies to access two years of an individual's metadata, are crucial to thwart terrorism attacks and prevent serious crime. The scheme is expected to cost up to $400 million a year, but the government won't reveal its share until the May budget. A government-commissioned review found the scheme would cost about $3.98 per customer each year if no taxpayer assistance was provided. Metadata includes the identity of a subscriber and the source, destination, date, time, duration and type of communication. It excludes the content of a message, phone call or email and web-browsing history.

Attorney-General George Brandis said telcos had been collecting this type of data for 20 years, however billing changes and the cost of storage mean it's more likely to be discarded. That degrades police and security agency investigations, he said. Labor backed the laws after the government agreed to a series of changes and a specific warrant safeguard for journalists. Palmer United Party Senator Zhenya "Dio" Wang also sided with the Coalition and Labor. The government did not win support from the Australian Greens or several crossbenchers, who fear the laws are an invasion of privacy.

Liberal Democrat David Leyonhjelm condemned the laws as an ineffective anti-terrorism tool, arguing that adding more hay to a haystack would not make it easier to find the needle. The Liberal Democrat accused Senator Brandis of being "more obedient to the Australian Federal Police than some of their sniffer dogs". Independent senator Jacqui Lambie said imposing the death penalty on convicted terrorists would be a more successful national security plan. The Greens unsuccessfully tried to amend the bill to require warrants for most metadata access and reduce the time frame for data storage from two years to three months. "If two dozen agencies want to know where you are at any time of the day ... and who you're talking to at any given time, get a warrant," Greens senator Scott Ludlam said.

Senator Brandis said it would be impractical to get a warrant for every access request, given last year there were 340,000 such instances.