The legal, ethical and societal implications of the digital revolution underway in the United States and across the world are likely to become "exponentially more complicated" with the advent of 5G, the next generation of faster and more stable mobile and web networks, according to the top lawyer at the country's largest intelligence agency, the National Security Agency (NSA).

Privacy considerations -- especially as artificial intelligence, geolocation and facial recognition technologies become more widespread -- may pose a particularly daunting challenge, said Glenn Gerstell, who serves as the NSA's general counsel.

"There's lots and lots of potential for mischief. There's lots of potential for real benefit. But I think our society hasn't even now, let alone in the future, figured out what privacy really means," Gerstell said. "We haven't been faced with a technology like this, that has become this ubiquitous, this impactful, ever in the history of the world."

In an interview with Intelligence Matters host and CBS News senior national security contributor Michael Morell, Gerstell said the sheer rapidity of the adoption and spread of new technologies is likely to pose challenges for regulators and legislators alike.

In the past, whenever new technologies developed -- like the telephone, electricity, the automobile -- "it took decades for the technology to become pervasive," Gerstell pointed out. "And during that period of time, we were able to sort the rules of the road out. We haven't worked that out yet in the cyber world. We are willing, seemingly, to tolerate some level of cyber insecurity."

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Speaking in a personal capacity, and not on behalf of the NSA, Gerstell said "significant legislative action" was likely "inevitable."

"And now the question is, will our country be able to get ahead of the technological revolution, or are we going to, for a number of years, be dealing with the problems before we can come up with a societal solution? It's yet to be seen," he told Morell.

Gerstell said recent changes in the digital and information landscape had also prompted changes within the NSA itself – the agency had semi-facetiously been dubbed 'No Such Agency' given the highly secretive nature of its functions.

But while the culture at the NSA is "definitely one of secrecy," he said — primarily in order to keep adversaries in the dark about U.S. capabilities — attitudes about transparency have evolved.

"We recognize that in this day and age, with so much information available to our citizens – which is a good thing – we can't hide behind the wall of secrecy completely," Gerstell told Morell. "And transparency, at some level, is appropriate, and we do that in the form of issuing annual reports on surveillance, by having the directors of the agencies testify in public before Congress."

"That didn't always happen at the early days of the agency," he said.

Gerstell acknowledged that the 2013 disclosures made by former contractor Edward Snowden had contributed to perceptions that the NSA was a rogue agency with bloated surveillance powers. But he argued that U.S. citizens should be reassured by these three factors: 1) the mission-oriented nature of NSA employees; 2) the agency's own robust compliance department; and 3) a rigorous oversight process with built-in redundancy by multiple federal bodies.

While the government can target any foreigner overseas for national security reasons, Gerstell told Morell, Americans are protected by the Fourth Amendment no matter where they are. And any surveillance of an American living in the U.S. or overseas requires a specific judicial finding at the probable cause standard, he said, "that either a crime is being committed, in the case of the United States, or that the person is an agent of a foreign power."

If surveillance of a foreigner results in incidental collection of communications with an American, he explained, there are procedures in place for "unmasking" the identity of that individual, whose identity is otherwise concealed in intelligence reports.

"You just can't say, 'I'd like to see the name here. This sounds interesting – tell me more.' You need to articulate why it is," Gerstell told Morell. "And assuming your position is such that it's appropriate and you annunciate a valid reason, then we will release the name."

He said any and all individuals who have been targeted for surveillance by the agency, for example, are reviewed by the Justice Department's National Security Division and the Office of the Director of National Intelligence. A privacy and civil liberties board, the president's intelligence advisory board, and two congressional committees also oversee the agency's functions.

"So there's lots and lots of layers of oversight, which consumes a lot of my time in addressing," he said. "I'm not in any way complaining about that."

"I think ultimately, the American people have to feel comfortable that with all these layers of oversight and congressional committees," he said.

"They're the ones who are able to – in connection with our transparency efforts – they're the ones who are able to provide the assurance that what we're doing is scrupulously within the law."

For much more from Michael Morell's conversation with Glenn Gerstell – you can listen to the new episode and subscribe to Intelligence Matters here.