MPP/RMX (Remain in Mexico)

Under the "Remain in Mexico" program (RMX), also referred to as the "Migrant Protection Protocols" (MPP), noncitizens who arrive at the southern border and ask for asylum are given notices to appear at a future date in a U.S. immigration court at the border, and then returned to Mexico to wait for however long it takes for the U.S. government to process their applications for humanitarian protection.  The program was created by President Trump in late 2018.  On the campaign trail, President Biden promised to end RMX, and attempted to do so soon after he was inaugurated; litigation ensued.