The National Security Agency is using the "best technology" available to ensure it doesn't collect U.S. communications while tapping the Internet’s backbone, the agency says.

That assurance is contained in a report released Friday by the Privacy and Civil Liberties Oversight Board about the spy agency’s compliance with recommendations from the five-member board.

The board – largely dormant before exiled whistleblower Edward Snowden’s June 2013 disclosures – has emerged as an active overseer of spy programs as it seeks to gain institutional credibility, issuing lengthy reports on phone- and Internet-record collection programs.

The oversight board said in its Friday release that the NSA either has complied or is in the process of complying with 22 recommendations issued in those reports. Some of the compliance is mandated by the USA Freedom Act, which ended the automatic bulk collection of domestic call records.

Without the force of law, the agency's compliance with recommended changes to Internet surveillance is murkier, though the NSA assured the board it’s doing a good job.

For example, in response to a panel recommendation, the NSA "determined that at this time the best technology is being used for filtering" intercepts from its “upstream” program to ensure domestic communications aren't collected, according to the report. The upstream program takes information directly from the routers, cables and switches that make up the Internet’s backbone.

The privacy board has insisted on such a review for the controversial collection, reasoning that “[e]ven if domestic communications were to constitute a very small percentage of upstream collection, this could still result in a large overall number of purely domestic communications being collected.”

If wholly domestic communications of Americans are incidentally collected, they currently can be stored and searched without a warrant – something that privacy-minded members of the House of Representatives have voted to forbid, but which congressional leaders have stripped from budget bills.

The board's report says the NSA also self-reported it was in compliance with a recommendation that the agency consider ways to limit “about” collection, through which communications containing a selection term are produced, though those communications do not necessarily come from intelligence targets.

“At least some forms of ‘about’ collection present novel and difficult issues regarding the balance between privacy and national security,” the oversight board said.

The report says the "NSA conducted a review based upon the Board’s recommendation and concluded that no changes are practical at this time" to limit "about" collection, though the agency said it would review the matter as technology evolves.

The American Civil Liberties Union is representing the Wikimedia Foundation – which operates the online encyclopedia Wikipedia – and several other plaintiffs in a lawsuit against the upstream collection program, claiming the collection is unconstitutional.

"The PCLOB’s status report offers little comfort, and only underscores that the NSA continues to copy and search Americans’ international Internet communications en masse," says ACLU staff attorney Ashley Gorski.

"That the NSA may be using the 'best technology' to conduct its searches is like saying it’s using the 'best investigator' to open and read through everyone’s letters," she says. "These kinds of dragnet, warrantless searches are unprecedented and are precisely what the Constitution forbids."

The ACLU's lawsuit was dismissed after an initial court hearing, but that ruling is being appealed. Another case filed nearly a decade ago by the Electronic Frontier Foundation against upstream collection is pending.

Upstream collection and a major Internet spy program exposed by Snowden called PRISM, which takes information directly from prominent Web companies, lean on Section 702 of the Foreign Intelligence Surveillance Act. Programs conducted under FISA are supervised to some degree by the Foreign Intelligence Surveillance Court, though critics accuse that body of being a rubber stamp for government requests.