A new study from Louisiana shows that immigrants who challenge their detention in court are much less likely to prevail before judges than to quietly get released by U.S. Immigration and Customs Enforcement while their cases are pending.

The study, conducted by Tulane University Law School’s Immigration Rights Clinic and shared with ProPublica, makes the case that what it calls “shadow wins” may allow ICE to uphold a status quo that frequently goes beyond the Supreme Court’s 2001 ruling that indefinite detention is unconstitutional.

Federal court challenges can be a detainee’s only hope of mandated release after months or years, especially in Louisiana, which has recently become a major detention hot spot. But the study finds those filings remain “complex, time consuming, and currently inaccessible for many detained immigrants.”

The report offers new evidence of the need for clear guidelines on how long immigrants may be detained without overstepping the Constitution. Under the Fifth Amendment, it is unconstitutional to hold immigrants without due process, but the Supreme Court has not clearly defined how long someone can be held without being deported before their detention becomes unconstitutional.

The Tulane researchers analyzed 499 federal court petitions filed by Louisiana detainees between January 2010 and June 2020. The filings, known legally as petitions for a writ of habeas corpus (or habeas petitions), asked federal judges to order their release.

In the cases, immigrants had been held in custody for an average of 13 months by the time they filed their petitions in federal court. While the study’s authors cautioned that they don’t have full records for all detainees’ immigration cases, because those happen in separate immigration courts run by the Department of Justice, their data shows that about three-quarters of detainees had been ordered deported but were still being detained.

By the time the legal cases were resolved, an additional several months had passed — often because ICE officials delayed filing responses for months. In one case analyzed by Tulane, an ICE official told the court that the detainee would be deported imminently. Seven months later, the deportation still hadn’t happened, though ICE once again said it was “imminent.” The detainee was ultimately held for an additional nine months — then released.

The Deep South has become a center for the detention of immigrants, and Louisiana is known as a state where detainees often languish in prolonged detention, partly because local ICE officials rarely grant parole. From Oct. 1, 2020, to May 13, 2021 (the most recent date for which ICE has data available), there was an average of 1,819 ICE detainees in Louisiana — the most of any state after Texas — accounting for 12% of detainees nationwide, according to data analyzed by ProPublica. But while the average detainee in Texas had been in ICE custody for 45 days, the average Louisiana detainee had been held for over 90 days.

In 2001, the Supreme Court suggested that detaining someone for six months after they received a deportation order could be unlawful. But the court has not set a firm standard for when prolonged detention turns into indefinite detention, either for immigrants who’ve been ordered deported or for those who are still fighting their cases through a backlogged immigration court system.

Without a clear legal standard, it falls to individual detainees to challenge their detentions. One of the detainees whose case was covered in the Tulane report told ProPublica that he found out about the option to file a petition when studying in the detention center library. He’s now assisting current detainees with habeas petitions, while awaiting a final decision in his immigration-court case; he spoke anonymously to avoid affecting his case’s outcome.

Immigrants almost never got favorable rulings; judges ordered a release in five of the nearly 500 Louisiana cases analyzed. In 112 of the cases, ICE released detainees while their petitions were pending, allowing the judge to dismiss the cases. These “shadow wins,” as the study authors call them, were almost as common as cases that ended because the immigrant was deported.

“Shadow wins” are good for the person getting released, but from the government’s perspective, they limit potential damage. They “avoid a precedent being set that would compel them to act in certain ways in future,” the detainee, whose case was covered in the report and who was trained as a lawyer in his home country, told ProPublica, “and that way they maintain the discretion that they enjoy.”

The Tulane study concludes that “because the releases end the legal case challenging detention, ICE may be using these releases to avoid negative court decisions that make formal rulings regarding prolonged, indefinite and punitive detention.”

During the COVID-19 pandemic, “shadow wins” also allowed government officials to avoid testifying about the real conditions in their facilities. The detainee said he was released from detention before an ICE official testified in his case. In other recent cases analyzed by ProPublica in Louisiana and Texas, “shadow wins” preempted disclosures about COVID-19. Chris Benoit, an El Paso lawyer who represented a group of women who were released after filing a habeas petition last summer, told ProPublica his clients were also released shortly before ICE officials were slated to testify. “In our case, there was a clear desire to not have a record on the part of ICE,” he said.

ICE did not respond to a request for comment.

Concerns about COVID-19 have compelled judges around the country to order ICE to release some detainees, and there are thousands fewer immigrants in detention than at the pandemic’s beginning (largely because of a policy in place since March 2020 that immediately expels most migrants caught entering the U.S. without papers, rather than detaining and deporting them). But those who are still detained are being held longer, as the pandemic has slowed both immigration courts and deportation flights. In fiscal year 2019, according to ICE statistics, the average detainee was held for 34 days; in fiscal year 2021 to date, the average is 72 days.

As part of the Biden administration’s “reset” of immigration enforcement, acting ICE Director Tae Johnson instructed the agency in February to limit detention to immigrants who are enforcement priorities because of criminal history or other concerns. But advocates say they’re still struggling to win the release of people who are already detained, even if they don’t fit those priorities. In the absence of federal court precedent, ICE still has discretion over who gets detained and for how long.