Beverly Gage, a Yale history professor, is the author of The Day Wall Street Exploded.

...There can be no question that COINTELPRO was more intrusive—if also more targeted—than today’s apparent efforts at mass technological surveillance by the National Security Agency. But there is at least one important distinction that makes today’s scandal far more disturbing. When the FBI launched COINTELPRO, it was acting alone, outside of the boundaries of established law. Today, what the NSA is doing appears to be legal—and nearly every branch of the government is complicit. Unlike Hoover’s activities, the NSA’s programs come to us with the seal of congressional and judicial approval. It didn’t take J. Edgar Hoover to engineer this scandal. We did it to ourselves....