A GP caught up in the Chelmsford deep sleep therapy scandal has been given another chance to clear his name after an appeal court found evidence from “dead experts” was wrongly used to throw out his multimillion-dollar defamation lawsuit.

Dr John Gill and former psychiatrist Mr John Herron both worked at Chelmsford Hospital in Sydney in the 1970s, where the controversial addiction therapy was blamed for the deaths of at least 23 psychiatric patients.

The pair originally sued ABC journalist Steve Cannane over his book, Fair Game: The Untold Story of Scientology in Australia, which explored the church’s role in exposing the scandal.

After an eight-week hearing last year, the Federal Court of Australia found the book’s imputations that they had been grossly negligent, were responsible for a number of the deaths and traumatised patients by administered deep sleep therapy without their consent were substantially true.