Title 42 dates back to a 1944 law known as the Public Health Service Act, which granted US health authorities emergency powers to prevent the spread of diseases.
In March 2020, the Trump administration invoked the statute with the stated intent of preventing Covid-19 from spreading in the US. The former president and his top advisers had also supported tightening and overhauling US immigration policy, and the president had run on a pledge to build a wall along the border with Mexico to keep migrants from entering the country.
Title 42 allowed the administration to quickly expel migrants trying to cross the southern US border with Mexico – including asylum seekers – using the coronavirus pandemic as a justification.
The Biden administration continued to defend the policy for over a year after the current president took office, and expelled about two million people under Title 42 in fiscal years 2021-22, according to US Customs and Border Protection’s data.