External oversight of an EMB is part of its external accountability, and may be implemented through mechanisms such as external audits or evaluations, reviews of EMB activities by an ad hoc or other specially appointed body, or reviews by a committee of the legislature, such as an electoral affairs or public accounts committee.

If an entity undertaking external oversight of an EMB is not fully independent, it may be subject to interference that improperly inhibits its oversight scope and/or methodology. There may be attempts to change or influence the contents of oversight reports. Constraints on oversight bodies may include restrictions on terms of reference, on time allowed for investigations, on access to information, or on access to sufficient funds and other resources to carry out the task. For example, the Indonesian election monitoring body, Panwas, both monitors the conduct of the election and is the body of first instance for most election disputes. While it is expected that Panwas act independently, it is appointed and funded by the EMB. Conflict in 2004 between Panwas and the EMB over Panwas’ challenges to EMB decisions led the EMB to remove any role for Panwas in challenges or disputes involving the EMB.

Oversight bodies need rights to examine documents and computer files, to verify services and property acquired with public funds, and to interview EMB members, staff, and other persons. These rights can be guaranteed if they are included in the legal framework. If not, the EMB can enhance its credibility by allowing free and unimpeded access. In many cases, official oversight agencies are given the authority to obtain court–enforceable subpoenas to compel the EMB and other organisations to produce specific documentation, with sanctions for non-compliance. Where an oversight agency is given investigative powers, it usually is able to administer and take affidavits under oath.

To be effective, oversight must be subject to rigorous quality control so that it is professional, impartial, and accurate.