Stephen Miller, the one-time senior advisor to former President Donald Trump who shaped immigration crackdown policies, has launched a new conservative group that could take on President Biden's progressive agenda in court.

Miller formed America First Legal, which aims to serve as a conservative counterweight to the American Civil Liberties Union (ACLU). The nonprofit organization intends to launch court challenges with state GOP attorneys general to fight back on executive actions they deem unlawful or an overreach.

Miller understands firsthand the legal challenges that Trump faced when he sought to implement new executive policies, from his travel ban on predominantly Muslim countries to building a southern border wall with military funds.