The door is locked.

A guard punches in a code and the door swings open, but it can take almost an hour to get inside the immigration court with the highest deportation rate in America — not counting the time it takes to drive there from Atlanta, almost 140 miles away.

Inside the jail at the Stewart Detention Center, judges in long black robes preside from their benches in courtrooms with cinderblock walls. Inmates in blue, orange, and red uniforms sit on wooden benches waiting to learn whether a judge will let them stay in the United States or send them away.

The court has all the trappings of the American judicial system, except for one of its most cherished principles: accountability. In immigration courts nationwide, files and evidence are kept from public view. Hearings are open, but not publicized, and are often held inside detention centers; the few outsiders who attend quickly discover that judges have broad powers to eject the public. Most judges’ full decisions are never even written down.

The secrecy conceals the inner workings of a controversial court system that renders life-altering decisions with little opportunity for public review once the hearing is over. Each year, immigration judges order some 160,000 people to leave the country, including more than 10,500 who asked for asylum because they said their home country was dangerous.

The 58 US immigration courts are overburdened and understaffed, carrying caseloads several times larger than regular courts and run by about 250 judges who have burnout rates that rival prison wardens, one study showed, partly because they make so much less money and have far less job security than other federal judges.

Half of the immigrants before the court have no lawyer to help them navigate the maze of immigration law, and the justice they receive depends heavily on who hears their case: for instance, some judges grant nearly all requests for asylum, while others deny each one, according to data collected by Syracuse University. Yet the judges’ words are usually final: Immigrants appeal fewer than one deportation decision in 10.

“They had a reason for putting it there,” said Wanda Tejeda, who lives down the street from the detention center in Lumpkin, where the population of the 1,700-bed facility outnumbers the whole town. “What better place to put it than a little town in the middle of the South in the middle of nowhere that nobody’s ever heard of?”

The officials who run the immigration courts acknowledge that they make public far fewer documents than regular courts, and that their courtrooms increasingly are located inside locked detention centers that are difficult for the public to get to. But they insist they are not trying to hide anything, and have also opened courts outside of jails.

Immigration courts are allowed to withhold many documents to better protect immigrants’ privacy because they are under the executive, not the judicial branch, explain the leaders of the Justice Department’s Executive Office for Immigration Review, which runs the courts. Officials say the three new courts they have placed inside detention centers over the last decade are simply a way to reduce costs, not to discourage public participation.

And the immigration officials say they are aware that so many immigrants don’t have lawyers, noting that they try to connect detainees with nonprofit groups that can help them understand the process and minimize their time locked up.

Juan Osuna, the office’s director, said in a written statement that his staff “is keenly aware of the many issues that respondents face.”

Maybe so, but the immigration judges at Stewart issued a deportation order to almost every immigrant who came before them last year, with many of the detainees giving up before they got a chance to fully make their case to stay. They are on an assembly line that often ends when immigrants, exhausted by incarceration, beg to be deported.