At the time of the murders, Dershowitz was just finishing a book called The Abuse Excuse--and Other Cop-Outs, Sob Stories, and Evasion of Responsibility.  Concerned that Dershowitz's thesis may negatively impact Simpson's case, Shapiro decided to hire Dershowitz, in part to "shut him up." Rarely present in court, Dershowitz spent most of his time handling motions and other support documents. His main assignment was to prepare for possible appellate review of an adverse trial outcome.

In his book, The Best Defense, Dershowitz gave a view of the approach he would later take in the Simpson case.  "Once I decide to take a case," Dershowitz wrote, "I have only one agenda: I want to win.  I will try, by every fair and legal means, to get my client off--without regard to the consequences."   In his memoir The Best Defense, Dershowitz noted that "almost all of my clients have been guilty."