The autobiography contains references to a 1991 inquiry by former conflict commissioner Ted Hughes, who found Vander Zalm used his public office to sell his Fantasy Gardens theme park.
Hughes, 84, has testified that he was depressed and shocked by what he read in Vander Zalm's 2008 book and sued because he was portrayed as having conducted an unfair inquiry.
B.C. Supreme Court Judge Laura Gerow said in her instructions to the seven jurors Wednesday that if they find Vander Zalm guilty of defamation, they could award damages.
Hughes' lawyer has asked jurors to award his client aggravated damages so Vander Zalm can't put any spin on what he called malicious attacks against his client.
Vander Zalm's lawyer has suggested Hughes' lawsuit is frivolous and that Hughes' reputation hasn't suffered as a result of the book, published 17 years after Vander Zalm was forced to step down.
Vander Zalm, now 77, defended the statements about Hughes, saying they were fair comments, not facts, and that they were made as a matter of public interest.
"The defence of fair comment will not be available to Mr. Vander Zalm if Mr. Hughes proves that the dominant purpose of Mr. Vander Zalm publishing the comment was malicious," Gerow told the five women and two men of the jury.
"It is for you to decide whether it was necessary for Mr. Vander Zalm to include the defamation statements in order to communicate on this matter of public interest."
Hughes, 84, claims the book paints him as someone who was self-interested, biased and politically motivated in finding Vander Zalm breached conflict of interest guidelines.
He said Vander Zalm suggested Hughes hid behind a mask of integrity and that the inquiry findings were part of a setup orchestrated by the NDP to appoint him as full-time conflict commissioner.
Hughes, a former Saskatchewan judge and B.C. deputy attorney general, was appointed to the job by Rita Johnson, who took over as Social Credit premier after Vander Zalm resigned.
Vander Zalm has testified his purpose in writing the book was to set the record straight and to encourage discussion about the closed-door inquiry process that he considered unfair.
However, court heard the former premier agreed to the process instead of a public inquiry and had stated beforehand that he would immediately resign if there was an appearance of a conflict of interest.
Vander Zalm sold Fantasy Gardens for $16 million in 1990 to Taiwanese billionaire Tan Yu.
Court heard the former premier asked Hughes to conduct the inquiry after controversy boiled over about Vander Zalm setting up meetings for Yu with his finance minister and the lieutenant governor.
The public furor also included a late-night hotel meeting between Vander Zalm and Yu, who, according to a witness who provided Hughes with a tape recording, handed the then-premier an envelope stuffed with $20,000 in $100 U.S. bills.
Hughes said in his report and in court that he didn't believe the explanations of witness Faye Leung, who brokered the sale of the property and provided the tape, or Vander Zalm, who told court he took the money for safekeeping.
Vander Zalm was acquitted of breach of trust in a criminal trial.