A B.C. Supreme Court civil trial jury delivered the verdict Thursday afternoon in Vancouver, with a recommendation that Vander Zalm pay Hughes $60,000 damages. The final damages amount will be up to the judge hearing the case, who will announce a decision at a later date.
Hughes had sued Vander Zalm for statements he made in a self-published autobiography.
Hughes headed an inquiry in 1991 that found then-premier Vander Zalm had violated the province's conflict-of-interest regulations during the sale of a theme park he owned.
The finding prompted Vander Zalm's resignation as premier.
In his 2008 autobiography, Vander Zalm suggested that Hughes was self-interested and politically biased in his conduct of the inquiry.
Hughes, 84, said he was shocked and depressed at reading the passages that referred to him.
Vander Zalm's lawyer told the court that the way his client portrayed key players like Hughes was fair comment.