Mr Fricker released the documents with much fanfare on Tuesday, although Professor Jenny Hocking, the driving force behind the documents' release, was stuck in Melbourne due to border restrictions.

The Archives have been criticised for not releasing the letters from Governor-General Sir John Kerr to the palace, but Mr Fricker said he was bound to act within the constraints of the law.

"While it was often reported that I or the National Archives had deemed these records to be personal and private, it was in fact impossible for me to take any other course of action given the decision of the full bench of the Federal Court," he said.

"And as I said all the way through that, and I'll say it again now, we are a pro-disclosure organisation. But we do things according to law."

The decision by the High Court to deem the letters Commonwealth records and ordering the Archives to reconsider Professor Hocking's request had allowed the institution to act as it normally would in assisting an historian, he said.

"The reason we're on the same page now is because I'm clear on what the law requires and now we're back in the normal relationship between archives and historians.

"It's a very symbiotic relationship, archives need historians and historians need archives because that's how records are brought to life and the knowledge is dispersed."

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Lasting years and making its way through the Administrative Appeals Tribunal, the Federal Court and the High Court, it has been estimated the saga has cost the Archives $2 million, but on Tuesday Mr Fricker said he hadn't added up the final figure. He also defended the spending of the money, even though the institution has limited resources.

"I can't not go to court. I mean, that would just be me avoiding public scrutiny.

"On the other hand, to say, 'well, why don't you save a bit of money and just do something which is not lawful, and that'll put that money back in your budget to do something else?' I can't do that," he said.

Mr Fricker said court cases like the one over the letters were "the cost of doing business" for the institution.

"I can't avoid legal accountability for the purpose of saving money."

The Archives are still to explore the full implications of the High Court decision for other correspondence between other governors-general and the palace.

"I do still continue to go through that judgment and have a look at how that impacts upon the other royal correspondence," he said.

While no governor-general had written as much to the Queen as Sir John Kerr, there were other records in the Archives and legal advice would now be sought on what the decision means for those documents.

"Nobody in my experience was quite as prolific as Sir John Kerr as far as the volume of documents, but nonetheless we do have documents of other governors-general."