Three years ago, many Americans being held prisoner in Mexican jails were agreeing to almost anything if it meant they could bid adios to old Mexico. Now serving the Mexican sentences in federal prisons here in the United States, some of these incarcerated U.S. citizens are having second thoughts about the bargain they struck.

About six years ago, investigative journalists and families of U.S. citizens arrested in Mexico -- usually for alleged narcotics transactions -- began reporting what they described as the horrendous conditions in jails there.

Congress investigated and verified that U.S. citizens were, indeed, being arrested and convicted of narcotics violations in Mexico without any semblance of what would be considered a fair trial in the United States.

Many former prisoners say such charges were trumped up and the arrests made to extort money from the prisoners or their families. The prisoner found himself or herself in a nightmare where the price of a bunk in a cell might go as high as $2,000. Those Americans who could not come up with the money from home were forced to fend for themselves in courtyards where they would often sleep tied up to bars to keep from falling into sewage that flowed past.

And they were, they claimed, savagely and sadistically tortured by the Mexican police on a regular basis. The Americans wrote frantic letters home, begging relatives to send money or to pay huge sums in person to certain Mexican lawyers who, the rumors went, could get sentences reduced.

Cruelty to, and extortion of, the U.S. prisoners allegedly became a profitable business.

News accounts and a public outcry eventually led to negotiations between Mexico and the United States seeking the transfer of the Americans to United States federal correction institutions.

Mexican officials were adamant that only their courts would have jurisdiction over proceedings to challenge or modify the Mexican convictions that led to the Americans' imprisonment. They did not want U.S. courts reviewing Mexican police conduct and trial procedures. As a compromise, the Mexicans agreed that U.S. law would be used to govern prisoners' parole eligibility once they were back in the United States.

The treaty was signed and ratified in 1977, after the United States agreed to the Mexican demand that U.S. courts keep hands off Mexican convictions. The Mexican demand and our agreement were not unusual. No country will tolerate its trial procedures being reviewed by a foreign court. And this country agreed to that condition because at the time the primary concern was to get the Americans out of Mexico.

The exchange began immediately. Before prisoners was permitted to leave Mexico, they had to agree not to challenge their sentences once back in the United States. The U.S. Department of Justice issued a booklet to Americans in Mexican prisons explaining the conditions for transfer. A federal magistrate dispatched to Mexico questioned each transfer applicant about his knowledge of the conditions imposed upon the transfer. He authorized transfer after satisfying himself that the prisoner agreed to the conditions and consented to the transfer knowingly and voluntarily, without threat or coercion.

Now three years after the transfer, prisoners serving out their Mexican sentences here are attempting to overturn their agreements not to challenge the Mexican convictions in U.S. courts. No one reading their accounts of what they allege happened to them in Mexico would fail to feel sympathy for their plight.

They were brutalized, they say. Convicted without ever having seen a judge. Imprisoned under the most inhumane conditions.

Measured by U.S. standards of due process of law, cause existed at every step of the proceedings to throw the Mexican court convictions out. Moreover, the U.S. Department of Justice, while opposing their petitions for habeas corpus in federal courts, did not dispute their descriptions of the conditions they endured or, even in some cases, the petitioners' claims of innocence.

The issues facing the courts considering the petitions were complex. The crux became whether these prisoners would be forced to live by the agreements they signed in Mexico not to challenge their convictions in U.S. courts.

One prisoner testified that he had agreed because of the intolerable prison conditions in Mexico. He said, "I would have signed anything at all to leave the country." Another testified that he agreed because it was the only opportunity to get out. When asked what he thought would happen to him if he remained in Santa Marta prison, he replied," I knew I was going to get killed. . ."

Two United States Court of Appeals have held that the prisoners' agreements were valid and that they waived their rights to seek habeas corpus in U.S. courts. The court for the Second Circuit sitting in New York said that the prisoners gave up this right in order to gain the advantages of better prison conditions and a chance for parole.

Just like the prisoners, the courts were not faced with a happy choice. If they had ruled in favor of the petitioners, the exchange treaty with Mexico would undoubtedly be dead. As Chief Judge Kaufman of the Second Circuit wrote, "Rather, we hold open the door for others similarly victimized to escape their torment."