Ingersoll's full-time occupation was an appellate attorney with the Cuyahoga County Public Defender Office in Cleveland, Ohio, until he retired in 2009.

Comic series he has written for include Donald Duck, The Green Hornet,[2] House of Mystery, Justice Machine, Mickey Mouse, Moon Knight and Star Trek: All of Me.

Since 1983 Ingersoll has written "The Law Is a Ass" (sic; the title comes from Mr. Bumble's dialogue in Charles Dickens' Oliver Twist and preserves the character's grammatical error), a regular column in Comics Buyer's Guide, which was also published online by World Famous Comics.com from 1999 to 2003.

[5] He is co-author (with fellow comic-book creator Thomas F. Zahler) of the short story "'Til Death", which was published in Star Trek: The Next Generation: The Sky's the Limit in 2007.

In 1987 (in the pages of Secret Origins #14), writer John Ostrander named a piece of legislation in the fictional DC universe the "Ingersoll Amendment".