[3] He earned a Bachelor of Arts, summa cum laude, from Brandeis University majoring in economics and minoring in Legal Studies.

In 2002 he returned to private practice as a partner at Cadwalader, Wickersham & Taft, where he focused on white collar defense, internal investigations, and regulatory compliance.

[4] The New York Times reported he was not among at least twelve inspectors general fired by President Donald Trump four days into his second term.

[6] Horowitz announced in January 2017 that the Inspector General's office would examine evidence related to "allegations of misconduct" regarding FBI Director James B. Comey's handling of the investigation into Hillary Clinton's email practices and whether Justice Department employees leaked information improperly during the run-up to the 2016 United States presidential election.

He found that Comey indulged in ad hoc decision making and did not follow FBI procedures, but did not find that he was motivated by any political bias.

[15] The report found that the FBI had a legal "authorized investigative purpose and with sufficient factual predication" to ask for court approval to begin surveillance of Carter Page, a former Trump campaign adviser.

[18] The findings led Rod Rosenstein, who had been Trump's Attorney General at the time the policy was enforced, to admit that family separations "should never have been implemented".