On Friday, the men entered pleas of not guilty to charges of conspiring between late 2007 and early 2009 over the grant by Macdonald, then mining minister, of a coal exploration licence at Mount Penny in the Bylong Valley.

The prosecution will allege the trio conspired that Macdonald would engage in wilful misconduct in public office by acting "without impartiality" or in breach of his obligations of confidentiality in order to benefit Obeid family interests.

Obeid snr and Macdonald, dressed in prison greens, looked haggard as they appeared in the NSW Supreme Court via audiovisual link from Silverwater and Cooma jails respectively. They are already serving prison sentences after being convicted of unrelated offences.

Moses Obeid, dressed in a navy suit, is on bail and appeared in court to enter his plea.

Prosecutor Sophie Callan told the court the trial was estimated to run for 22 to 23 weeks - or almost six months - excluding four weeks of pre-trial applications.

Additional jurors may need to be empanelled in light of the length of the trial.

A high-profile terrorism trial in 2009 ran for a historic 10 months, with a jury of 15 selected from a pool of 5000 potential jurors. Twelve jurors remained at the end of the trial.

Ms Callan estimated the Crown case alone, including opening and closing addresses and 44 witnesses, would take up to nine weeks.

Counsel for the Obeids, expected to include Robert Richter, QC, and Stuart Littlemore, QC, have estimated the defence case and closing addresses would take eight weeks.

Macdonald's defence and closing address are expected to take about three weeks.

But David Mackay, for Macdonald, told the court his client was "currently without funding for his trial".

Justice Peter Johnson said the trial would begin on March 4, 2019, and would be listed with an estimate of "up to 23 weeks".

The matter will return to court for a preliminary hearing on November 3, when Justice Johnson said he hoped to be able to reveal the name of the trial judge.

In addition to the parties' submissions, the trial judge will need time to deliver his or her summing up to the jury before deliberations commence.

Obeid was jailed in December last year for a maximum of five years over his secret business dealings at Circular Quay.

Macdonald was sentenced in June to a maximum of 10 years in prison for granting a coal exploration licence to Doyles Creek Mining, a company chaired by former union boss John Maitland.