"Gentlemen do not read each other's mail." That's what Secretary of State Henry Stimson said to explain why he shut down the government's cryptanalysis operations in 1929.
Edward Snowden, who leaked National Security Agency surveillance projects to Britain's Guardian, evidently feels the same way.
"I can't in good conscience allow the U.S. government," he explained, "to destroy privacy, Internet freedom and basic liberties for people around the world with this massive surveillance machine they're secretly building."
Some questions about this episode remain. How did a 29-year-old high school dropout get a $122,000 job with an NSA contractor? How did his job give him access to material including, he says, Foreign Intelligence Surveillance Agency Court documents?
And why did he flee to China's Special Autonomous Region of Hong Kong and make his revelations just before the Sunnylands summit, where Barack Obama was preparing to complain to Xi Jinping about China's cyberwarfare attacks?
Oh, and now that he has checked out of his Hong Kong hotel, where has he gone?
All tantalizing questions. But some other questions that many are asking have clear answers.
Is the NRA surveillance of telephone records illegal? No, it has been authorized by the FISA Court under the FISA Act provisions passed by (a Democratic) Congress in 2008.
The NSA is not entitled to listen to the contents of specific phone calls. It has to go back to the FISA Court for permission to do that.
Under the Supreme Court's 1979 Smith v. Maryland decision, the government can collect evidence of phone numbers called, just as the government can read the addresses on the outside of an envelope.
Snowden presented no evidence that the NSA is abusing its powers by accessing the private information of those with obnoxious opinions. There is, so far anyway, no evidence of the kind of political targeting committed by the Internal Revenue Service.
Instead the NSA is looking for patterns of unusual behavior that might indicate calls to and from terrorists. This data mining relies on the use of algorithms sifting through Big Data, much like the data mining of Google and the Obama campaign.
Snowden also exposed the NSA's PRISM program, which does surveil the contents of messages -- but only of those of suspected terrorists in foreign countries.
During George W. Bush's administration, many journalists and Democrats assailed this as "domestic wiretapping." But the only time people here are surveiled is when they are in contact with terrorism suspects in foreign countries.