Federal prosecutors are urging that a Palestinian Arab activist spend the rest of his life in prison for refusing to testify before a grand jury investigating Hamas links in America.

Earlier this year, a jury in Chicago convicted Abdelhaleem Ashqar, 49, of contempt of court and obstruction of justice. However, jurors acquitted Ashqar of participating in a racketeering conspiracy to support Hamas, a terrorist group responsible for a string of bombings and other attacks that killed hundreds in Israel, Gaza, and the West Bank.

Despite the jury’s decision to acquit Ashqar on the most serious charge, prosecutors filed a legal brief Wednesday arguing that a probation officer’s recommendation of a life sentence for contempt was “correctly calculated.”

“Defendant Ashqar remains defiant, and to this day keeps locked within himself information and evidence directly relating to the domestic and international support network through which the Hamas terrorist organization perpetuated its long reign of terror, and in the process has allowed the directors and facilitators of that reign of terror to evade … legal sanction,” the prosecution team from the office of U.S. Attorney Patrick Fitzgerald wrote. “That defiance reflects defendant Ashqar to be a continuing threat who is not capable of rehabilitation.”

There is no statutory limit to Ashqar’s sentence because he was convicted of criminal contempt, a crime for which Congress has set no maximum punishment. Other alleged Hamas activists who lied to or defied courts have received sentences of a year or two in prison. Obstruction of justice carries a maximum prison sentence of 10 years.

Ashqar’s attorney, William Moffitt, who has argued that a life sentence would violate the Constitution’s ban on “cruel and unusual punishment,” was not available for comment yesterday. However, another defense lawyer involved in the case, Michael Deutsch, called the government’s stance “Kafkaesque.”

“It’s really a very scary application of justice and the sentencing law,” Mr. Deutsch said. “They don’t give any credit in their pleading to the acquittal. It’s just as if it didn’t happen.”

A former federal terrorism prosecutor, Andrew McCarthy, said the prosecution was going too far in seeking a life term for contempt of court. “That’s a very dangerous thing to recommend,” he said. “Isn’t 10 years enough?”

Mr. McCarthy said prosecutors were going against the grain of a series of recent Supreme Court decisions urging greater deference to juries. “If you’ve been acquitted, that acquitted conduct shouldn’t be shooting the [sentencing] guidelines through the roof. I think the Supreme Court is going to find that to be a very troubling constitutional issue,” he said.

“My attitude about terrorism is, ‘Lock the door and throw away the key,’ but when somebody gets acquitted on a major count — I like to win, but it’s a fact of life — you have to modulate your expectations,” Mr. McCarthy said.

Mr. Fitzgerald’s team contends that case law in the 7th Circuit allows Ashqar to be punished for facilitating murder and terrorism even if the related conspiracy charge was not proved beyond a reasonable doubt.

Judge Amy St. Eve is scheduled to sentence Ashqar on November 8.