Duty and its Source

The lawyer-client relationship has historically been characterised as one of confidence. This duty also constitutes part of the broader foundation for lawyer's fiduciary duties to their clients.

Rationale for the duty
The maintenance of full and frank disclosure between lawyers and their clients is the main justification for the duty of confidentiality. It allows clients to freely discuss intimate details without fear that such information could be subsequently disclosed to the general public. In turn, public confidence in lawyers and the legal system is maintained and promoted. Further, the duty of confidentiality is a constant reminder to lawyers of the loyalty they owe to their clients.

Source of the duty
The duty is sourced from a combination of contract law and equity arising from the distinctive relationship between lawyer and client. In contract, the duty arises from terms contained in the retainer agreement. Complementarily, equity prohibits unauthorised use or disclosure of confidential information. In most jurisdictions, the duty is codified in the terms of legal professional rules.
Although the duty of confidentiality and fiduciary duties have common origins, they cannot be equated as not all fiduciary duties attract duties of confidentiality and vice-versa.