The owners of the Algo Centre Mall will have to turn over more information to the Elliot Lake public inquiry.
The commission is looking into the events that led to the deadly mall roof collapse last summer.
The Nazarian family has already turned over tens of thousands of emails to the commission, but argued several hundred more should remain confidential, citing solicitor-client privilege.
However, the commission of the inquiry disagreed and took the matter to an outside expert for a ruling.
Appeal Court Justice Stephen Goudge decided most of the documents must be turned over to the inquiry, including information that contains communication with a demolition company and a real estate agent.
Some of the communication between the Nazarian family and their lawyer concerns legal advice and will remain private, Goudge decided.
The commission hearings will resume again next week in Elliot Lake.
Levon Nazarian and his father, Bob, are scheduled to testify starting July 15.
Following the testimony from the Nazarians, the inquiry will move into phase two, examining the rescue efforts in the days following the roof collapse.