The man who authorised federal police to raid ABC's Sydney headquarters failed to define how far officers could search, the public broadcaster alleges.
The ABC has launched Federal Court action over the raids at its Ultimo offices on June 5, seeking the search warrant be set aside and the seized files returned.
The AFP has made an undertaking it will not access the seized material until at least July 9, pending the outcome of the ABC's application.
Court documents released on Wednesday reveal the grounds on which the ABC is challenging the warrant's validity, including that the document did not "provide a real and meaningful perimeter" about what was allowed to be searched and seized.
The raids were in relation to stories published in 2017 alleging Australian soldiers may have carried out unlawful killings in Afghanistan, based on leaked Defence papers.
During the search, AFP officers took possession of about 100 documents on national security grounds. The contents were transferred to USB sticks and placed in sealed bags.
By law, to issue a warrant the court officer needs to state the warrant's related offences and be satisfied with several issues including that there are reasonable grounds for suspecting the material is or soon will be at the premises.
In its application filed in the Federal Court, the ABC argues NSW Local Court registrar Martin Kane did not comply with those requirements or several others, "in a way that constitutes an abuse of power".
The public broadcaster argues the references to suspected crimes were in a manner that was "conclusionary, vague and uncertain" and, on one occasion, not applicable.
"Kane's decision to issue the search warrant was legally unreasonable," it says.
The application also makes reference to the "implied constitutional freedom for the reasonable discussion of government and political matters" and the "public interest in investigative journalism".
It says no reasonable person in Mr Kane's position would have authorised the warrant while having regard to those matters above and the "alleged unlawful killings" and gross dysfunction revealed in stories known as The Afghan Files.
A related document describes the ABC's investigative and public interest journalism as "fundamental to the maintenance of the Australian system of representative democracy under ... the constitution".
A full hearing on the matter is not expected until late July or early August.
ABC managing director David Anderson this week said the organisation would use every avenue "to defend the actions of its journalists and to seek legislative changes that protect the media's ability to report on matters of public interest".
Australian Associated Press