A U.S. citizen’s six-year fight to hold FBI operatives accountable for his detainment and torture in East Africa is again at risk of being quashed by the government, in a move that risks denying judicial remedy for those mistreated by U.S. officials abroad.

Amir Meshal, a 32-year-old man born in New Jersey to parents of Egyptian descent, remains “deeply traumatized” from being held in “stark and inhuman conditions without charges or legal basis” by U.S. officials, his lawyers say.

While detained, Meshal was threatened by FBI agents with mental and physical abuse and told that he would be made to “disappear,” their lawsuit alleges.

Judges have described his case as troubling and the allegations against the U.S. government as embarrassing. But attempts to hold any U.S. parties accountable have repeatedly been denied.

On Friday, Meshal lawyers argued in an appeal hearing that if the case is dismissed again, innocent American citizens who are illegally detained and mistreated by U.S. personnel abroad would have no judicial recourse.

“The implications of this case are far reaching,” wrote Jonathan Hafetz, Meshal’s lawyer and an American Civil Liberties Union cooperating attorney.

“If the court accepts the government's arguments for dismissal,” Hafetz said, “it will effectively give U.S. law enforcement — from the FBI to the DEA — carte blanche in their treatment of any of the millions of American citizens who live, work and travel abroad.”

In June 2014 a U.S. District Court for the District of Columbia dismissed Meshal’s case on the basis of a national security exception. The defendants argued that the court did not have jurisdiction and deciding the case would “undermine the government’s ability to speak with one voice in this area.”

If the latest appeal fails, it will provide a further setback for Meshal, whose ordeal began a decade ago.

In 2005, Meshal, who grew up in the U.S., went to Cairo to live with members of his extended family. A year later he traveled to Mogadishu, Somalia, to study Islam but was forced to flee violence as Ethiopian forces entered the country to fight insurgent groups, he said.

Along with other foreign civilians, he headed to the Somali border town of Ras Kamboni, where armed Somalis ordered them into a truck and then released them into a forest, according to the federal suit.

Meshal said he spent weeks wandering the forest with four other people until in late January 2007 heavily armed Kenyan soldiers surrounded them and took them to the town of Kiunga, where Meshal was jailed. He was soon flown to Mombasa and then to Nairobi.

For four months and three days, he was denied access to a lawyer, held in three countries (in addition to Kenya, he was rendered to Somalia and Ethiopia), interrogated more than 30 times and threatened by U.S. officials “with torture, forced disappearance and other serious harm in order to coerce him to confess to wrongdoing in which he had not engaged and to associations that he did not have,” the lawsuit alleges.

In May an Ethiopian guard went to his cell and — without explanation — released him. On May 27, 2007, he was returned to the U.S., having lost 80 pounds. In all that time, he was never charged with a crime.

Meshal alleges that he was jailed, questioned and psychologically tortured, though not physically harmed, by four FBI agents — Chris Higgenbotham and Steve Hersem and two others called “Tim” and “Dennis,” whose identities are known but not allowed to be publicly released.

Higgenbotham and Hersem were identified in another case, involving Texas resident Daniel Maldonano, who was seized on the Somalia-Kenya border in 2007.

Meshal said he has severe mental anguish and has suffered from the loss of income and livelihood. He is suing only the U.S. agents who he alleges were directly involved in his detention and treatment.

The U.S. government is not denying the allegations or contesting them, merely arguing that Meshal’s Fourth and Fifth Amendment rights to a prompt hearing and due process don’t apply in cases involving national security issues abroad.

Last summer, a U.S. District Court judge said that he was outraged by Meshal’s “appalling (and, candidly, embarrassing) allegations” of mistreatment by the U.S. but that the court had to deny him judicial remedy because the court was “constrained by binding precedent.”

The judge’s opinion, however, stated that denying Meshal any recourse “raises serious concerns about the separation of powers, the role of the judiciary and whether our courts have the power to protect our own citizens from constitutional violations by our government when those violations occur abroad.”

Meshal’s lawyer told Al Jazeera on Monday that the U.S. government’s position is “incredibly sweeping” and “nontransparent.”

Meshal “could have been held for four years, he could have been beaten to death or close to it,” and it “wouldn’t matter if this happened in Kenya … or in London,” Hafetz said. The government's national security argument would be the same, he said, and Meshal would have noplace to seek justice.

During Friday’s appeal hearing, one of the three panel judges asked the Justice Department attorney if “a U.S. citizen can be tortured, killed abroad by an FBI agent without remedy under your theory of the case?”

The judge added, “It’s troubling to think about the FBI and CIA … any U.S. official can detain a U.S. citizen forever without remedy.”

The Justice Department lawyer responded that national security concerns are cause for caution and that there were foreign governments involved in Meshal’s mistreatment.

Steve Vladeck, a professor of law at American University Washington College of Law who filed a brief on behalf of Meshal, wrote in an email that the case has “major implications for all Americans overseas.”

“Given the ever-broadening reach of the U.S. government overseas … the need for some judicial remedy to ensure that government officers aren’t immune for misconduct solely because it takes place across a border becomes that much more manifest,” he wrote.

A decision in the case is not expected until later this year.