AFL boss Gillon McLachlan may be cross-examined in court about the league's handling of the Essendon supplements saga after losing a bid to stop the issue becoming the subject of a full Supreme Court trial.
McLachlan, former AFL chairman Mike Fitzpatrick and the league are fighting a case brought by lawyer Jackson Taylor which alleges they engaged in misleading and deceptive conduct.
In January 2016, anti-doping authorities suspended 34 Essendon players for 12 months for their involvement in the supplement program run by the club four years earlier.
When details of the program emerged in 2013, the AFL suspended coach James Hird for bringing the game into disrepute, fined the club $2 million and kicked the side out of that year's finals series.
Mr Taylor's case relies on a series of statements made by McLachlan and Fitzpatrick in media interviews in the 13 months from January 2016, including that the AFL had exercised reasonable care in protecting the health and safety of Essendon players, and had not asked the Australian Sports Anti-Doping Authority to remove material unfavourable to the AFL from its interim report.
The AFL had applied for a preliminary hearing in the case which would limit the number of witnesses called and discovery of documents.
It had hoped to avoid a full trial which it argued would cost $700,000 to prepare, and involve thousands of documents, people who no longer work for the AFL, the league's executive including former chief executive Andrew Demetriou, and legal department.
But Justice John Dixon ruled the preliminary issues should not be heard separately and a full trial should proceed.
McLachlan and Fitzpatrick are likely to be called as witnesses.
"The court will have to consider the same or related questions in the context of a full trial," Justice Dixon said.
"Such duplication of effort may prolong proceedings rather than shorten litigation and may unfairly disadvantage the plaintiff."
There will be a preliminary hearing on a more confined issue before a trial date is set.
Mr Taylor has no direct financial interest in prosecuting his claim, but has told the court he had brought the legal action in "the public interest".
The AFL was ordered to pay Mr Taylor's legal costs in fighting the application.