The purpose of the Laken Riley Act is to enhance the enforcement of immigration laws concerning non-citizens who are charged with theft-related crimes in the United States. This legislation aims to ensure that individuals who are not legally in the country and have been involved in theft offenses are detained by immigration authorities. Key provisions of the Act include a requirement for the Secretary of Homeland Security to take custody of non-citizens charged with theft, burglary, larceny, or shoplifting.