Beginning in 2022, Posner began service as Counsel to the Assistant Attorney General for Antitrust at the United States Department of Justice.

[12] In June 2013, Posner and Jameel Jaffer, fellow at the Open Society Foundations, participated in The New York Times Room for Debate series.

[13] Posner responded to concerns about expanded National Security Agency (NSA) programs that vacuum information about the private lives of American citizens.

Posner in 2013 argued that since 2001 there had not been a single instance of "war-on-terror-related surveillance in which the government used information obtained for security purposes to target a political opponent, dissenter or critic".

[15] In 2018, Posner co-wrote an article advocating a system of market-oriented, privately sponsored work visas as a supplement to U.S. immigration policy.

In particular, he argues that the American legal system's deeply rooted basis in cognitive science often eschews, or has yet to develop, significant acknowledgement of the role emotions play in criminology and contract theory.

[17] For example, a person who commits a criminal act while in an emotional state may receive a harsher or lighter punishment depending on whether they were motivated by hatred or shame.