Remain in Mexico policy

The Remain in Mexico policy, officially the Migrant Protection Protocols (MPP), was announced by the U.S. Department of Homeland Security in December 2018 and began implementation in January 2019 at the San Ysidro port of entry. Under MPP, non-Mexican migrants—primarily from Central America—who arrived at the U.S. southern border seeking asylum could be returned to Mexico for the duration of their U.S. removal proceedings, rather than being detained in the United States or released into the country pending hearings.

The legal basis cited by DHS was section 235(b)(2)(C) of the Immigration and Nationality Act, which permits the return of certain arriving aliens to a contiguous territory. Mexico, under the Andrés Manuel López Obrador administration, agreed to accept returnees and provide humanitarian protections, though it did not formally sign a safe-third-country agreement.

Critics, including the UNHCR and organizations such as Human Rights First, documented assaults, kidnappings, and extortion targeting migrants waiting in Mexican border cities like Tijuana, Ciudad Juárez, and Matamoros. Supporters argued the policy deterred frivolous asylum claims and reduced strain on U.S. detention capacity.

The Biden administration suspended new enrollments on 20 January 2021 and formally terminated MPP later that year. However, in Texas v. Biden (2021), a federal district court ordered reinstatement; the U.S. Supreme Court ruled in Biden v. Texas (2022) that the administration had the statutory authority to end the program. MPP was wound down in August 2022.

Key features delegates and researchers should note:

• Applied only to non-Mexican nationals arriving by land from Mexico.
• Excluded unaccompanied minors and, in practice, many vulnerable categories—though enforcement of exclusions was inconsistent.
• Tens of thousands were enrolled; DHS data cited roughly 70,000 cases by early 2021, though figures vary by source.
• Operated alongside, and was later overshadowed by, Title 42 public-health expulsions during the COVID-19 pandemic.