The Bill of Rights section of the US constitution, and its well-established legal interpretations, forbid mass intrusions into people's privacy. Only a court order, based on "reasonable cause" for suspecting an individual to have committed a crime, can allow intrusion into the privacy, home, documents or other aspects of that person's life. The massive surveillance of phone calls, e-mails and other online actions and messages of millions of Americans clearly violates the constitution, and can, without exaggeration, be called "treason".

The US president, for example, upon taking office, takes an oath to "protect and defend the constitution". The members of US Congress have similar obligations. Yet many of them have lashed out at Snowden, instead of criticizing the program that has violated one of the most basic democratic rights of Americans.

Fortunately, there are exceptions. Former US vice-president Al Gore has said the NSA surveillance program does violate the constitution. "This in my view violates the constitution. The fourth amendment and the first amendment - and the fourth amendment language is crystal clear (on this matter)," he said.

Congressman Ron Paul has also spoken out against the surveillance program, saying that the problem is not Snowden but what he has revealed: the violation of the US constitution.

Of course, there are people who claim cyber surveillance and cyber espionage are necessary to prevent terrorism. This argument, to say the least, is absurd.

To begin with, no one believes that China is involved in terrorism, yet hundreds of the cyberattacks have been aimed at China. Germany, the European Union country most targeted by the cyber surveillance program, is not involved in terrorism either.

As Ivan Eland of the conservative Independent Institute in US says: "The US constitution makes no exception for national security, and terrorism specifically." And he emphasizes that the chances of an American being killed by a terrorist are "about the same as getting killed by an asteroid or lightning. Terrorism is a very rare event."

Snowden himself was asked in Hong Kong about the anti-terrorism argument used to justify the massive surveillance and spying program. He said: "We managed to survive greater threats in our history ... than a few disorganized terrorist groups and rogue states without resorting to these sorts of programs. It is not that I do not value intelligence, but that I oppose omniscient, automatic, mass surveillance. That seems to me a greater threat to the institutions of free society than missed intelligence reports, and unworthy of the costs."

Finally, three former NSA employees praised Snowden in an interview published on Sunday by USA Today newspaper, and corroborated a number of key points made by him. All three previously held important positions in the NSA, and supported Snowdens' claim that there is massive and illegal surveillance of US citizens online and telephone communications, and that he has given evidence of an "institutional crime".

The author is a Canadian scholar living in Beijing.