The AEC is headed by a Commission consisting of three people appointed by the Special Minister of State:
- a chairperson, who must be a current or retired judge of the Federal Court selected from a list of three nominees given by the Chief Justice of the Federal Court
- a non-judicial member, who is almost always the Australian Statistician (the head of the Australian Bureau of Statistics)
- the Electoral Commissioner, who acts as the day-to-day CEO of the AEC and is responsible for actually running elections.
None of these appointments can be terminated except by the Governor-General with cause. The same goes for the Deputy Electoral Commissioner, and the Australian Electoral Officer for each State/Territory (who is responsible for certain electoral functions in each state, and is usually also the AEC's State Manager).
Now, the Commission isn't directly responsible for drawing up electorate boundaries. That task goes to the Redistribution Committee for the State/Territory, which is assembled every time a redistribution is required.
The Redistribution Committee consists of:
- the Electoral Commissioner
- the AEO for the State
- the State's Surveyor-General
- the State's Auditor-General
The Surveyor-General and Auditor-General are state officials. The Auditor-General is usually covered by similar protections as the Electoral Commissioner - i.e. they can't be dismissed without legitimate cause.
After the committee has done its work and approved a proposed map (through several rounds of public consultation and public objections), the map has to be approved by the Augmented Electoral Commission, which consists of all three members of the Electoral Commission plus the other members of the Redistribution Committee for that state/territory.
There is absolutely no route of appeal to any court against a decision of the Augmented Electoral Commission to approve a redistribution proposal, as long as it complies with the Constitution - the process depends on the members of the committee acting in an unbiased manner and following the requirements that the law sets out for defining fair boundaries.
Outside of redistributions, the AEC requires all its employees to be "politically neutral" (i.e. not to participate in political activities such as campaigning or openly expressing personal political views) and to sign declarations accordingly.
When it comes to the actual conduct of elections and referendums, results can be appealed to the High Court as the Court of Disputed Returns, which can choose to inquire into whatever matters it needs to understand to determine whether the result of an election is valid.
More generally, the AEC reports to the Parliament's Joint Standing Committee on Electoral Matters which provides political oversight. Other oversight bodies like the Australian National Audit Office and the Commonwealth Ombudsman can also investigate the AEC. However, these bodies can only review the AEC's operations and give advisory recommendations - they don't have any power to direct the AEC.
So overall, the AEC's neutrality is ensured by:
- all senior officers being protected by law from arbitrary dismissal, thus encouraging independence from government interference
- the Commission, which oversees the AEC's work, being headed by a member of the judiciary and with oversight from another senior public servant
- redistributions being conducted with the help of state officials who are similarly non-partisan public servants, and conducted according to regulations which mandate multiple rounds of public consultation
- all employees being required to be politically neutral
- the AEC's permanent staff being drawn from the Australian Public Service which is generally non-partisan
- oversight from the Parliament and other Commonwealth oversight bodies
In contrast, most US states have redistricting conducted by partisan members of the Legislature who are not required to give regard to fairness, and electoral officials are often openly partisan elected officers like the Secretary of State.
Of course, a lot of the AEC's reputation is based on the non-legal norms they have traditionally upheld, and successive Australian governments haven't really tried to mess with the AEC's independence. It remains to be seen how resilient their structure is if that situation were to change.