On Thursday, the Supreme Court dealt a blow to a humanitarian program that protects immigrants who can’t safely return to crisis-stricken countries. The decision effectively allows the Trump administration to move forward with terminating Temporary Protected Status (TPS) for more than 350,000 nationals of Syria and Haiti who are living and working in the United States.

It also paves the way for the administration to potentially end the protection for several other countries experiencing wars, environmental disasters, and extraordinary circumstances. That push, which the American Civil Liberties Union (ACLU) has called the “largest de-documentation event in US history,” could strip away legal status from more than 1.3 million TPS holders from 17 designated countries.