Dempsey said he believes some policymakers will continue to advocate for last year's controversial Justice Department proposal to preserve certain data on Internet activity. The good news, he mused, is that "Europe is further down the wrong road than the U.S. is."

As the momentum builds for Internet service providers to store data for law enforcement use, federal agencies "are drowning in information," Dempsey pointed out. "They are getting referrals from ISPs that they can't follow up on. Their response is 'give us more information so we can drown even quicker,'" he said.

As lawmakers and stakeholders contemplate how such a data retention mandate would be implemented, Gelman said it is important to realize that technology has changed over the years. "A lot of privacy protections we had 10 years ago were based on frictions in the system [that no longer exist]," she said. It used to cost more money to keep data for longer periods of time but "those disincentives have gone away," she said.