The bulk collection of phone “metadata” by the National Security Agency – records of who’s calling whom, when and for how long – is a tool that could, if abused, reveal sensitive facts about nearly every American’s life.

The practice, disclosed by former NSA contractor Edward Snowden, demands extensive checks to guard against misuse. The government has said its oversight process is already strong. To varying degrees, a federal judge and a task force appointed by President Obama now have disagreed.

The task force would like to see a higher legal standard applied before the government can access phone records. It reportedly proposed an end to the bulk collection of records, instead calling on the NSA to approach phone companies and ask for records as needed. Government officials have voiced concern that investigative speed may be lost in the interest of privacy protection.

To make such a case, they will have to do better in demonstrating the national security benefit of the running five-year phone-records database. On Monday, U.S. District Judge Richard J. Leon signaled skepticism on that score as he issued an injunction to prevent the bulk collection, citing Fourth Amendment restrictions on unreasonable searches.

Rejecting the applicability of a 1979 ruling, Leon argued that Americans’ relationship with technology has changed drastically now that cellphones and tablet computers are so ubiquitous and powerful. The government’s ability to collect information in bulk and hold it in perpetuity changes the context decisively from the 1979 case. Moreover, he wrote, in none of the examples the government cited was immediate access to phone records necessary.

If the government is to emerge from Edward Snowden’s revelations with the authorities that officials insist are crucial, it will have to do more to demonstrate why the NSA’s activities are essential and how Americans’ privacy is being protected.