Lawyers for former senator Rex Patrick have argued a judge was wrong to find the delays in freedom of information claims were not unreasonable.
Mr Patrick last year took the Australian Information Commissioner to the Federal Court over his FOI delays, claiming he waited more than three years for a decision on his requests.
He sought for the court to examine how long it takes the commissioner to make decisions and to outline what was an unreasonable delay.
There is no legal obligation for the commissioner to reach a decision within a specific period of time.
Justice Michael Wheelahan in May found the commissioner had limited resources to undertake the volume of reviews before her and the delays were due to an "unquestionable shortage of resources".
The justice said it would be inappropriate for the court to evaluate the commissioner's workload, assess her priorities or determine how she should best manage those limited resources.
Mr Patrick's case would also involve "inappropriate judicial interference with the decisional freedom of an executive body", Justice Wheelahan said.
Mr Patrick on Monday appealed the decision before the full Federal Court, with his barrister Stephen McDonald SC arguing Justice Wheelahan reached the wrong conclusion.
Mr McDonald said the years-long delays meant the commission was not carrying out its statutory functions and therefore the delays were unreasonable.
The lack of adequate resources could explain the drawn out time frames but it should not make an otherwise unreasonable delay legally sound, Mr McDonald said.
The commissioner's barrister, Zoe Maud SC, told the court Justice Wheelahan made the correct decision when finding the delays were not unreasonable.
She said it was open to the justice to consider the resource constraints and workload of the office when coming to his findings.
The full court will hand down its decision at a later date.
Mr Patrick said it was important that Australians could scrutinise government and participate in democracy through FOI claims.
"It seems that transparency is a word that's only shouted from opposition benches," he told AAP outside of court.
"It's a broken system. The government has to pay attention to it."
