Tony Abbott’s captain’s pick for the Royal Commission into Trade Union Corruption and Governance will need to decide on Friday whether to disqualify himself from the commissioner role due to his plans to deliver a speech at a Liberal Party fundraiser.

Former High Court Justice Dyson Heydon, who was appointed to the court by John Howard, yesterday claimed he had overlooked initial emails stating that the annual Sir Garfield Barwick Address he had agreed to give was a Liberal Party event, despite several emails mentioning the party’s association with the event.

Heydon is facing pressure to resign his role after Fairfax revealed last week that Heydon was set to deliver the address later this month.

At 4pm yesterday, Heydon issued directions that the Australian Council of Trade Unions must provide written submissions for an application for Heydon’s dismissal to the commission by 2pm on Thursday, before a special hearing on Friday at 10am, at which Heydon will, seemingly, decide whether Heydon is to be disqualified from the Royal Commission into Trade Union Corruption.

On ABC radio this morning the ACTU’s Dave Oliver said that the union was still considering its options.

Emails released last week initially indicated Heydon had pulled out of the address on the day the story broke — but before publication — because the dinner event could be seen to be a party political event. The government argues it is not a fundraiser because at $80 a head, it isn’t raising much in the way of funds for the New South Wales branch of the Liberal Party.

The ACTU is seeking to have Heydon removed from the commission and yesterday sought other emails related to Heydon’s decision to give the lecture. Yesterday Heydon released dozens of emails and argued he had “overlooked the connection between the person or persons organising the event and the Liberal Party of Australia” in a March 2015 confirmation email. Heydon agreed to speak in April 2014, at which time the royal commission was expected to finish up in December 2014. The commission is now due to report in December 2015.

The April 2014 email reveals a number of mentions of the Liberal Party’s association with the event.

“I am chair of one of the lawyer branches of the Liberal Party NSW Division,” the third paragraph of Gregory Burton’s email states. “Although we are formally a branch of the party, our aim is to be a liberal-minded ‘bridge’ to the profession rather than overtly party-political (although we trust we show the party in a favourable light!)”.

The email goes on to state that Attorney-General George Brandis and former prime minister John Howard have given the address in the past.

Heydon began scoping topics of discussion for the speech in March this year. The event will be held in August, and he wanted to give the address around the topics of “the judicial stature of Chief Justice Barwick viewed in the modern perspective”.

In June, after the date had been settled, Burton sent Heydon a copy of the “save the date” invitation. The subject of the email started with “FW: Liberal Party of Australia (NSW Division)-Lawyers’ Branch and Legal Policy Branch”. Heydon has said he did not see the attachment to the email, which was a flyer for the event, and includes a prominent logo for the Liberal Party.

The event invite also allows for people unable to attend the dinner to make a donation to the Liberal Party.