The ongoing saga of Mujahedin-e-Khalq is a good example of how the unfortunately imprecise cliche ought to be understood.
Iranian nuclear scientist Mostafa Ahmadi-Roshan's car, in which he was killed by an explosion. (Reuters)
In his new book, The Tyranny of Cliches, Jonah Goldberg goes on a rant against the phrase, "One man's terrorist is another man's freedom fighter," writing, "It is simply absurd to contend that because people may argue over who is or is not a terrorist that it is therefore impossible to make meaningful distinctions between terrorists and freedom fighters." Is that what those who invoke the phrase are saying? Like a lot of cliches, it doesn't really make literal sense and is probably best avoided, but I suspect what many people mean when they use it is something like, "As a descriptor, terrorist is almost never applied rigorously and consistently to describe the tactics a group is using -- rather, it is invoked as a pejorative to vilify the actions only of groups one wishes to discredit. People who agree with the ends of the very same groups often don't think of them as terrorists, the negative connotation of which causes them to focus on what they regard as the noble ends of allies they're more likely to dub freedom fighters."
Put more simply, it's possible to rigorously determine who is a terrorist if you go by the actual meaning of the word, but in practice the term is almost never applied in accordance with a strict definition.
And today I can alert you to an especially Orwellian example.
Back when the Bush Administration wanted to go to war in Iraq, despite the fact that it had nothing to do with 9/11, they did their best to persuade terrorist-hating Americans that Saddam Hussein was a sponsor of terrorism. For example, the Bush White House published a document called "Saddam Hussein's Support for International Terrorism." Check out this bullet point especially:
Iraq shelters terrorist groups including the Mujahedin-e-Khalq Organization (MKO), which has used terrorist violence against Iran and in the 1970s was responsible for killing several U.S. military personnel and U.S. civilians.
Nowadays, Iran is Public Enemy Number One. Mujahedin-e-Khalq, also known as MEK, is still a terrorist organization. That is to say, it both uses violence to terrorize civilian employees of the Iranian regime and appears on America's official list of foreign terror-sponsoring organizations. But various prominent Americans are being paid big bucks to help get MEK off the official list of terror groups.