The organization that runs the online encyclopedia Wikipedia had another day in court Thursday challenging U.S. internet surveillance, and judges reviewing the case expressed skepticism about authorities’ claim there was insufficient grounds to sue.

Oral arguments don’t always indicate how judges will rule, but the panel seemed puzzled about how the National Security Agency’s "upstream" collection of communications directly from the internet’s background would not affect the large Wikimedia Foundation.

Last year, U.S. District Judge T.S. Ellis dismissed the case on the grounds that Wikimedia and allied organizations relied on "probabilities and suppositions" and could not show their records were taken.

American Civil Liberties Union attorney Patrick Toomey told the three-judge panel of the U.S. Court of Appeals for the 4th Circuit, however, that it’s clear from records released since whistleblower Edward Snowden’s 2013 leaks that Wikimedia is affected.

Justice Department attorney Catherine Dorsey insisted that's just speculation, which derailed a similar case in 2013 before Snowden's revelations.

“How that is done is not public information,” she said about upstream collection, which authorities acknowledge lifts communications from cables that make up the internet’s backbone. “They speculate that must mean everything is being collected and there is no support for that allegation.”

The judges asked skeptical questions of Dorsey, displaying confusion about how the upstream program would not affect users or staff of one of the world's most popular websites in its task of spying on terrorists and other foreign targets.

Upstream collection is – along with the PRISM program that takes communications from companies like Google and Facebook – a major source of internet records the NSA says it's authorized to acquire through Section 702 of the Foreign Intelligence Surveillance Act.

The ACLU says the program violates the First and Fourth Amendments and exceeds the NSA’s statutory authority. Procedures to minimize collection of extraneous information about "U.S. persons" – citizens, legal residents, corporations or groups – are “feeble,” the lawsuit says, with intercepts stored three years by default and forever if encrypted.

Judge Andre Davis used a hypothetical in an attempt to understand how upstream collection could possibly be narrowly performed, asking: “If you want to know about every federal Article III judge, the law school from which she or he graduated, wouldn’t you search a database of every federal Article III judge?”

Davis said an alternative method might include visiting the alma maters.

“How do you go visit the alma mater of a person when you don’t know the identify of that person’s alma mater?” he said, illustrating reason to believe upstream collection works through mass interception of records.

Dorsey said the precise way the program operates remains classified but offered a vision for how it might not involve searches of all internet traffic.

"Each submarine cable has subcables and each of those subcables has up to 1,000 fiber-optic fibers on which the communications transit," she said. "As a technological matter the government would not have to collect the communication on a whole subcable … and the plaintiffs have offered no allegation that the government must collect everything."

Toomey said later in the hearing that description was misleading and that the ACLU intended to rebut it going forward.

Judge Diana Gribbon Motz struggled to reconcile Dorsey's description of the program as potentially limited with how it is understood to work.

“I don't understand how the government would do a very good job if it proceeded as you suggest,” she said. “I’m heavily for national security, but if they want something more than to and from they’re going to have to look at everything.”

Upstream collection works by taking records "to," "from" or "about" a selection term, according to a 2014 report by the Privacy and Civil Liberties Oversight Board.

The board wrote: "If the NSA therefore applied its targeting procedures to task email address 'JohnTarget@example.com,' to Section 702 upstream collection, the NSA would potentially acquire communications routed through the Internet backbone that were sent from email address JohnTarget@example.com, that were sent to JohnTarget@example.com, and communications that mentioned JohnTarget@example.com in the body of the message."

That report said that as of 2011 the NSA was collecting about 26.5 million internet transactions a year through upstream collection, after first attempting to filter out domestic communications and then screening the remainder for selection terms.

Judge Albert Diaz, distinguishing Wikimedia from several other groups represented by the ACLU, said the government’s established interception of communications from major internet chokepoints could allow for a conclusion Wikimedia was affected.

“They don’t need the dragnet allegation with respect to Wikimedia if you accept their allegation that because of the nature of their traffic it traverses across all of the chokepoints and if the government is surveilling some of them inevitably it’s going to sweep up some of that traffic," he said.

Even if the Wikimedia lawsuit is unsuccessful – or stalled in litigation for years as is a similar lawsuit brought by the Electronic Frontier Foundation against the PRISM program – the debate about NSA internet surveillance will continue.