The sensational claim was made in Isleworth Crown Court in Middlesex, England on Tuesday (26Nov13) ahead of the fraud trial of two women, Italian sisters Francesca and Elisabetta Grillo, who worked as personal assistants for the pair for over a decade.
They stand accused of using a credit card belonging to the couple between 2008 and 2012 to lavish themselves with gifts.
A judge presiding over the hearing allowed the Grillos' lawyer to read an email as part of their defence, in which Saatchi told his ex-wife that the defendants "would get off" because Lawson was "so off your head on drugs you allowed them to spend whatever they like."
In the email, Saatchi added: "Yes, I believe every word they said."
Lawson's legal team have vehemently denied the accusations, branding the claims "totally scurrilous".
The couple split earlier this year (13) after pictures seemingly showing the art dealer grabbing the Tv star by the throat appeared in the press.