Raised in Pompton Plains, New Jersey,[1] Cahill graduated from Pequannock Township High School.
"[8] He then served as a law clerk to Judge James B. Loken of the U.S. Court of Appeals for the Eighth Circuit from 1999 to 2000.
[3][9] Over that time, Cahill was involved in nearly every aspect of the school’s operation, including curricular oversight and reform, support for faculty research, admissions and financial-aid policy, budgetary planning, supervision of administrators and staff, maintenance and improvement of Law School facilities, external relations, and fundraising.
[9][3][5] He served as co-dean and professor at Rutgers Law School from 2016 to 2019, taking the post at 44 years of age.
[14][9][15][16] Cahill lives in Boerum Hill, Brooklyn with his wife, Rosalyn Scaff[17] and two children.