Granting Edward Snowden clemency, as many have urged, would send a terrible message to other potential whistle-blowers. Yes, he may have sparked an important national privacy debate, but he did so through reprehensible actions that harmed national security.

If that's a harsh verdict, I have earned the right to it. In terms of sheer media hype, I was the Snowden of my day, a disaffected ex-spy who, in the late 1970s and early '80s, rocked the security community by publishing a memoir about intelligence failures I'd witnessed as a CIA officer during the last years of the Vietnam War. I did so only after the agency backhanded my repeated requests for an in-house review of our mistakes and refused to help me or anyone else rescue Vietnamese allies abandoned during the evacuation of Saigon.

Ex-NSA leader Edward Snowden Credit:Getty

Government prosecutors never accused me of betraying classified secrets. But in 1980, the Supreme Court decided that I had "irreparably harmed" national security by publishing my book without official approval, in violation of CIA non-disclosure agreements. This, the court said, harmed the government's ability to prevent serious leaks.

The ruling left me destitute, stigmatised and gagged for life, required to clear with the CIA all my spy-related writings, including this one, with the threat of jail time if I screw up. The First Amendment also took a hit with the rulings in my case. Now, all intelligence alumni, Snowden included, can be severely punished for merely speaking out about their work, regardless of whether what they say contains any classified information.