Research on Internet activity unsurprisingly suggests that innocent Americans chilled their own online curiosity in the wake of Edward Snowden's revelations. If you know that the FBI is keeping an eye out for BIEs, how likely will you be to attend a Black Lives Matter protest, even if you have no intention to commit a crime? And although the FBI's counterintelligence document notes that "mere advocacy" of a particular view "may not constitute extremism, and may be constitutionally protected," the use of the word "may" leaves the FBI with plenty of leeway.