The main purpose of this legislation, known as the Public Safety First Act, is to enhance public safety by allowing the Secretary of Homeland Security to take custody of certain non-citizens who are charged with theft-related crimes in the United States. The goal is to ensure that individuals who have committed or are accused of serious offenses are detained, thereby preventing potential risks to the community. Key provisions of the Act include amendments to existing immigration law that specify the circumstances under which the Secretary of Homeland Security must detain non-citizens.