There are no internationally agreed guidelines for the external audit of SAIs. The possibility and scope for external audits are determined by the constitutional and legislative frameworks of each country and vary from case to case. The International Organisation of Supreme Audit Institutions (INTOSAI) provides international guidelines on key principles for SAIs, although these guidelines do not address the process of external audit. In addition, INTOSAI encourages peer reviews of SAIs and a sub-committee of the organisation is currently drawing up guidelines to standardise this process. The existence and strength of wider accountability mechanisms for SAIs need to be examined on a case-by-case basis since these mechanisms are tied to the particular legislative frameworks and organisational set-up that apply in a given country. There are three broad models of organising SAIs: the Westminster model, the Board or Collegiate model, and the Judicial model, each with different implication