The ongoing Russia probe framed the Senate Judiciary Committee's routine hearing to re-up Section 702 of the Foreign Intelligence Surveillance Act — a law that allows U.S. surveillance of foreigners as a counterterrorism strategy.

Why it matters: Prominent Republicans have raised concerns about parts of Section 702 in light of leaks that prompted the Russia probe. Sen. Lindsey Graham alluded to Michael Flynn's downfall at the hearing and asked point blank: Did you monitor my conversations?

Sen. Dick Durbin expressed concerns that the NSA said it could not provide a count of how many people are being watched. "How are we supposed to believe that transparency is really the guiding principle?" Durbin asked.

One of the most controversial parts of Section 702 is how the NSA records conversations about foreign agents. Earlier this year, the NSA announced it was stopping some "about" collection. But the NSA's Paul Morris said he was "nervous" about legally amending the "about" collection.