Before joining the USC faculty in 1989, she was Professor of Law at Harvard University, where she was one of the youngest woman in the school's history to receive tenure.
[12] On January 10, 2008, Estrich joined Quinn Emanuel Urquhart & Sullivan, LLP, a law firm based in Los Angeles, where she chaired their Public Strategy in High Profile Litigation: Media Relations practice area.
[13][14] Estrich was outspoken during the 2008 presidential race, particularly on the subject of women in politics in light of the candidacies of Hillary Clinton and Sarah Palin.
[16] Estrich and the former American Civil Liberties Union president in Massachusetts, Harvey A. Silverglate, joined attorneys representing two alleged Boston al-Qaeda funders, Emadeddin Z. Muntasser and Muhammed Mubayyid who were indicted on May 11, 2005, for lying about the true nature of their organization and their charitable, tax-exempt activities.
In their October 5, 2006, motion for dismissal, attorneys Estrich, Malick Ghachem, Norman Zalkind and Elizabeth Lunt, argued that the defendants lawfully exercised their religious freedom and obligation to give "zakat" (Islamic charity).
In July 2016, Estrich was retained as legal counsel to the former Fox News chairman Roger Ailes — whom she met on the George H. W. Bush campaign trail in 1988 and whom she considered a close friend.
Her attacks against Gabe Sherman, the New York reporter who broke the scandal, were negatively viewed by some who felt the representation to be inconsistent with Estrich's pro-feminist philosophy.