At issue is “temporary protected status,” a provision of immigration law that allows the government to grant temporary work authorizations and protection from deportation to undocumented immigrants from certain countries where life remains dangerous. Conditions that could merit the status include armed conflict and civil war, natural disasters, epidemics and “other extraordinary and temporary conditions.”

The status is intended to be temporary, but many of the designated countries have had their crises continue for years, resulting in certain groups’ protections lasting for decades.

In the next six months, the Trump administration will weigh whether to extend the status for several countries whose immigrants have lived in the United States for as long as 20 years — with a decision to end that status potentially upending their lives. All told, more than 440,000 people in the United States are protected by the program.