Mr. Lindh, a 21-year-old from Marin County, Calif., who had served as a Taliban soldier in Afghanistan, faced charges that could have sent him to prison for the rest of his life. In a plea deal, though, the government dropped its most serious accusations, including charges that Mr. Lindh had engaged in terrorism and conspired to kill Americans.

Mr. Lindh instead acknowledged only that he had aided the Taliban and carried weapons. He was sentenced to 20 years, and people congratulated his lawyers for their triumph.

Times change. Passions cool. Other cases offer telling contrasts. And Mr. Lindh now has a powerful and understandable case of buyer's remorse.

''He was a victim of a hysterical atmosphere post-9/11,'' Frank R. Lindh said about his son. ''Much like the country has reassessed the premises for the Iraq war, it should re-examine the premises for this sentence.''

To hear Frank Lindh tell it, his son was an earnest and confused student of Islam who took up arms in a civil war between the Taliban and the Northern Alliance. ''A very substantial number of people in America believe John fought Americans or committed terrorism or supported terrorism,'' Frank Lindh said. ''That's just not true.''

Related Resources United States Sentencing Guidelines Manual, 2006 Edition The United States Sentencing Guidelines Manual contains the text of the United States Sentencing Guidelines, with Policy Statements and Commentary of the United States Sentencing Commission Counter-Terrorism After 9/11: Justice, Security and Ethics Reconsidered This timely book provides the reader with a sense of the breadth of government activity, its nature, and the surrounding controversies, by looking at the many different facets of the war on terrorism.

But John Walker Lindh is not serving time for terrorism or treason. And he made a considered decision to accept a 20-year sentence.

On the other hand, two men accused of quite similar conduct managed to make much better deals. They had the good fortune, it turned out, to be held by the military rather than by civilian authorities, and they probably also benefited from the fact that the memory of the Sept. 11 attacks had receded a little by the time they sat down to negotiate.

Consider Yaser Hamdi. Mr. Hamdi, who held Saudi and American citizenship, was captured along with Mr. Lindh and was also accused of helping the Taliban. But he was detained as an enemy combatant and never charged with a crime.

A few months after the United States Supreme Court ruled that Mr. Hamdi could challenge his detention in 2004, he was sent to Saudi Arabia (''in civilian clothes and unhooded,'' as stipulated in his deal with the government) in exchange for giving up his American citizenship and agreeing to restrictions on his ability to travel. He is home and free.

Last month, in the first guilty plea before a military commission at Guantanamo, David Hicks, an Australian, admitted to more serious crimes than Mr. Lindh had. He was sentenced to nine months and should be home and free before the end of the year.

Mr. Lindh's situation, by contrast, keeps getting worse. In February, for reasons the government will not explain, he was moved from a medium-security prison in California to the maximum- security prison in Florence, Colo., one of the toughest in the federal system. He is 26 now, and his lawyers say that even with credit for good behavior he has 13 more years to go.

Dean Boyd, a Justice Department spokesman, said the department was evaluating a commutation request from Mr. Lindh. ''It is important to remember,'' Mr. Boyd said, ''that the sentence was the result of a negotiated plea agreement between Mr. Lindh and the government and was handed down by an independent federal judge.''

Mr. Boyd declined to discuss why the military justice system seems to be meting out more lenient punishment for similar conduct beyond saying that what takes place at Guantanamo ''is separate and distinct from the U.S. criminal justice system.''

Still, aspects of the experiences of Mr. Lindh, Mr. Hamdi and Mr. Hicks were quite similar. All have said, for instance, that they were subjected to abusive interrogations, but all gave up their right to sue over them. All acknowledged that the United States could again decide to capture and detain them as enemy combatants even after they were freed.

And all were at times denied access to lawyers who sought to represent them. The Federal Bureau of Investigation, over the objections of the Justice Department's own ethics lawyer, interrogated Mr. Lindh without a lawyer after his family had retained one for him.

Jesselyn Radack, the lawyer who gave the ethics advice, left the department in 2002 over its conduct in the Lindh case. Ms. Radack has continued to follow the case, though, and she cannot find a way to harmonize the punishments meted out to the three men.

''One guy is sitting in jail for 20 years,'' she said. ''The other guy is scot-free. And the third will serve nine months.''

If you buy a house and the real estate market moves against you, that is your tough luck. The legal system takes a similar attitude toward defendants who regret the plea agreements they made. That means Mr. Lindh is out of legal options.

He has instead thrown himself on the mercy of the pardon system. Federal pardons and commutations are a matter of executive grace, decided by the president, and they can take into account any factors, including whether, with hindsight and experience, the punishment still fits the crime.

Copyright 2007 The New York Times Company