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Jill Sanborn, the assistant director of the FBI's counterterrorism division, "baffled" experts during her congressional testimony about the Jan. 6 Capitol riot Wednesday.

The reason the FBI missed so many of the threats in the lead up to the attack was because the bureau does not believe it has the authority to monitor public social media unless there's predication, like an open investigation, Sanborn testified. The explanation left Rachel Levinson-Waldman, the deputy director of the Liberty and National Security program at The Brennan Center, perplexed, especially after she detailed the FBI's policies on the matter for Just Security last month.

In that piece, Levinson-Waldman noted "there are no constraints" on FBI agents' ability to sift through public social media content even "before opening any kind of inquiry."

Once an investigation is open, the FBI has even more leeway such as creating an undercover account or entering private chatrooms and forums, Levinson-Waldman wrote, adding that there are concerns about the latitude of the agency's authority "in light of its documented history targeting and surveilling communities and activists of color."

Levinson-Waldman didn't accuse Sanborn of delivering false testimony, but she argued that there's at least "a very basic disagreement" over the policies, and "it would be extremely helpful for Sanborn to elaborate on this."

The Wall Street Journal's Dustin Volz was also confused, pointing to some of his past reporting that found the FBI is, in fact, quite proactive on this front. Tim O'Donnell