The United Nations High Commissioner for Refugees (UNHCR) Thursday joined a growing group of organizations critiquing the United States’ reimplementation of its Migration Protection Protocols (MPP) program, also known as “Remain in Mexico.” The Biden Administration restarted the Trump-era MPP this month after a Supreme Court order held that President Biden’s cancellation of the program was arbitrary and capricious.

MPP, first instituted by the Trump Administration, required that asylum seekers arriving on the southern border with Mexico wait in Mexico while their claims were adjudicated, rather than in the United States. Advocates for MPP claimed that the program restored order to a chaotic asylum process on the border, while critics alleged that conditions in Mexico were unsafe for asylum seekers and that turning individuals away from shelter in the US violated international refugee law. Updated US Department of Homeland Security guidance was issued on Thursday after the Government of Mexico agreed to an updated form of MPP that promised greater transparency, a commitment to timely processing, and COVID-19 mitigation strategies.

Despite these changes, the UNHCR Representative for the United States and the Caribbean, Matthew Reynolds, expressed serious concerns about the MPP in a Thursday statement, saying that MPP would have an impact on “asylum seekers’ safety and their due process rights.” He added that the adjustments to the policy “are not sufficient to address these fundamental concerns.” Reynolds then distanced the UNHCR from the policy, saying that “UNHCR was never involved in implementing MPP and will not be supporting the reinstated policy”.

These concerns were mirrored by a Thursday statement from the American Civil Liberties Union (ACLU), which called the MPP “a humanitarian catastrophe” with an “underlying purpose being to deter people from seeking asylum by trapping them in miserable and dangerous conditions.” The ACLU called for the Biden Administration to end the program immediately and allow asylum seekers into the US while their cases are pending.

Article 33 of the 1951 UN Convention Relating to the Status of Refugees prohibits the return of refugees to territories where their lives may be endangered, also known as the practice of refoulement. Critics of MPP argue that its practice constitutes refoulement in violation of the 1951 Convention and other principles of international refugee law.