On Sept. 23, some 700 people marched on the White House, demanding freedom for the so-called Cuban Five, and over the past few weeks, meetings have been held around the country with the same demand.

This seems to puzzle, and perhaps irritate, many Americans. As a neighbor of mine put it: “They were sent up to spy on our government, weren’t they? And weren’t they convicted of espionage? So how can anyone say they didn’t get what they deserved?”

But the answer is: No, they were not sent up to spy on our government. Rather, they were sent up in the early ’90s to penetrate, and provide information on, Cuban exile organizations suspected of terrorist activities against Cuba, organizations such as Brothers to the Rescue, Alpha 66, Omega 7 and others.

And no, they were not convicted of espionage. They were not even charged with espionage. The activities of the Five had to do with obtaining information on the activities or plans of private, nongovernmental groups, which is not a crime.

And so, to have something to charge them with, the federal government turned to “conspiracy to commit espionage.” In other words, it alleged, they had agreed among themselves that at some unspecified future time, they would spy on the U.S. government.

However, there was not a shred of evidence to back that up, nothing to indicate that was what they intended. But not to mind. The lack of evidence bothered the jury not at all.

Another common misconception is that whatever the Five were doing here, it must have been intended to do harm to the U.S.

But again, no, the intent was not to do any harm to the United States; rather, it was to gather information on the illegal activities of these exile organizations and then, since Cuba could not act on it, to provide that information to U.S. authorities. And this was done.

In the summer of 1998, the Cuban government invited representatives of the FBI to Cuba, where they were handed a memorandum documenting terrorist activities on the part of a number of Miami organizations and urged to take action against these violations of U.S. law.

But the FBI took no action at all against any exile organization. Rather, in the fall of 1998, it arrested the Cuban Five on charges of conspiracy to commit espionage — almost certainly because it suspected them of having provided the information in the memorandum. In short, the FBI moved not against the terrorists, but against their accusers!

The Five — Gerardo Hernandez, Rene Gonzalez, Ramon Labanino Salazar, Antonio Guerrero and Fernando Gonzalez — were put on trial in November 2000, convicted on June 8, 2001, and given sentences ranging from 15 years to two consecutive life terms.

Were the Five altogether guiltless? No. They were, admittedly, the unregistered agents of a foreign government, a transgression that might at most have resulted in a few years jail time — or less, given that they had provided to the U.S. information that could have been crucial, had the U.S. chosen to use it.

By all rights, they should have long since been released. Rather than that, they have now been in prison under difficult conditions for over eight years, and facing a lifetime more.

Perhaps the most unjust case of all is that of Hernandez, who had penetrated the Brothers to the Rescue organization and was charged with conspiring with members of the Cuban military to murder four members of that organization whose two planes were shot down in or near Cuban airspace in 1996. But the charge is utterly absurd.

Brothers to the Rescue had long been overflying Cuban territory. In January 1996, the Cuban government issued a public warning that if they came in again, they would be shot down. A diplomatic note was sent to the U.S. government, again demanding that it take measures to halt such flights. It did not. On Feb. 24, three Brothers to the Rescue aircraft, heading for Cuba, were warned by the Havana tower to turn back. They did not. Two planes were shot down, resulting in four deaths.

An overreaction on Cuba’s part, yes, with tragic consequences, but Hernandez had nothing to do with it. Indeed, that a jury could find them guilty of so phony a charge I would take as proof that these men could not possibly receive a fair trial in Miami.

Three judges of the Eleventh Circuit Court in Atlanta seemed to think so: In August 2005, they revoked the sentences and ordered a new trial in a location other than Miami.

But, in August 2006, after apparently having been prodded by higher authorities, the entire Eleventh Court rejected the three judges’ decision reversing the sentences, denied a new trial and ordered the case to be sent back to the panel for its consideration of remaining aspects. We will see what comes of that.

Meanwhile, a grave injustice has been done to the Five and the credibility of the U.S. system of justice has been tarnished. This is a wrong that must be corrected. Our honor demands it.

Wayne S. Smith is a senior fellow at the Center for International Policy (ciponline.org) and an adjunct professor at Johns Hopkins University.

He is former chief of the U.S. Interests Section in Havana (1979-82). This article originally appeared in the South Florida Sun-Sentinel and is reprinted by permission of the author.