“It’s a colossal waste of our time to now have to reorganize hundreds of thousands of cases to deal with language issues and then there’s no interpreter,” Ms. Tabaddor said.

The small number of interpreters who do have a basic grasp of indigenous languages are still often ill-equipped to help — they must explain legal terms that are difficult to comprehend in any language and there are significant differences between regional dialects.

With migrants who cannot understand or be understood, lawyers and immigration experts say, there is no way to ensure fairness in court.

“We have an entire infrastructure set up where the default language is Spanish, but there are thousands of people coming to the southern border who can’t communicate that way — and they basically become invisible,” said Blake Gentry, a researcher who estimates that as many as a third of the migrants crossing the border through Arizona do not speak Spanish.

Immigration courts across the country have seen a steady rise in speakers of indigenous Guatemalan languages in the last five years, according to the Justice Department’s Executive Office for Immigration Review, which oversees the court. And they are only the most recent additions to the list, which for several years has routinely included Zapotec, Mixtec, Ixil and Popti, languages from southern Mexico and Central America.

“The lack of interpretation for indigenous people has been a problem for a long time,” said Odilia Romero, a Zapotec interpreter who has been an activist with the Binational Front of Indigenous Organizations for the last 20 years. “But what we see now is something entirely different: We have entire populations showing up with languages that we have not seen in the United States before.