The principle in Mann v Carnell (1999) 201 CLR 1 (‘Mann’) is that legal professional privilege over a communication is impliedly waived where disclosure and use of the communication is inconsistent with maintaining the confidentiality provided by the privilege. However, in AWB Ltd v Cole (No 5) (2006) 155 FCR 30 (‘AWB’) – another leading case on implied waiver – Young J devoted several paragraphs to discussing waiver of ‘associated material’ relating to other waived communications (at –).
In both Zantran Pty Ltd v Crown Resorts Ltd [No 2]  FCA 1024 (‘Zantran’) and Perth Airport Pty Ltd v Qantas Airways Ltd [No 2]  WASC 342 (‘Perth Airport’), it was argued that there was a waiver of associated material as described by Young J in AWB. Together, these decisions are helpful in understanding whether there exists an ‘associated material waiver’, and the relationship between the inconsistency principle and associated material. This case note first discusses O’Callaghan J’s decision on a point of law in Zantran, before considering its application by Le Miere J in Perth Airport.
Zantran Pty Ltd v Crown Resorts Ltd [No 2]  FCA 1024:
In Zantran, O’Callaghan J was required to determine whether there exists a recognised species of waiver called ‘associated material waiver’. Counsel for Zantran argued that passages from Young J’s judgment in AWB stood for the proposition that ‘a voluntary disclosure of privileged documents can result in a waiver of privilege over those documents and associated material’ and that ‘[t]he test applied to determine the scope of any waiver of associated material is whether the material that the party has chosen to release from privilege represents the whole of the material relevant to the same issue or subject-matter’. As put by O’Callaghan J in Zantran, it was submitted that ‘the voluntary provision of one privileged communication gives rise to a waiver of legal professional privilege over all other privileged communications relevant to the same issue or subject matter as the communication voluntarily provided’ (at ).
Counsel for Zantran relied on the following passage from AWB (inter alia): ‘Turning to the scope of any imputed waiver, it is well established that a voluntary disclosure of privileged documents can result in a waiver of privilege over those documents and associated material. The test applied to determine the scope of any waiver of associated material is whether the material that the party has chosen to release from privilege represents the whole of the material relevant to the same issue or subject matter’ (at  of AWB). Counsel for Crown argued that the only guiding principle for the waiver of legal professional privilege at common law is the inconsistency principle stated in Mann.
Justice O’Callaghan noted that the difference between the two submissions might be ‘more apparent than real’, but that ‘[i]n either case, the critical anterior question is to identify the relevant issue or subject matter’ (at ).
His Honour said that when there is an express waiver, ‘an issue arises about whether and to what extent privilege has also been waived with respect to “related” non-disclosed documents’, which might be described as ‘associated material’. However, O’Callaghan J rejected the submission that Young J’s judgment in AWB establishes a separate species of waiver relating to ‘associated material’ which expands the Mann principles (at –).
Perth Airport Pty Ltd v Qantas Airways Ltd [No 2]  WASC 342:
Zantran was recently applied by Le Miere J in Perth Airport. In that case, Qantas sought production for inspection certain documents which record analysis and advice by Houston Kemp (an economic consulting firm) and Dr Mundy. Perth Airport claimed legal professional privilege on the grounds that the documents were communications between the advisers and Perth Airport or their solicitor that were prepared for the dominant purpose of giving or obtaining legal advice (at ). Justice Le Miere ultimately found that Perth Airport had, during negotiations with Qantas and other airlines, waived legal professional privilege in respect of certain advice from Houston Kemp, and that production of documents communicating that relevant analysis was necessary for disposing fairly of the proceeding (at , , –).
In relation to the scope of the order for production, Qantas also sought production of any material necessary to understand that analysis or which underpinned or influenced it, and any documents referred to in particular documents containing the analysis (at ). That is, Qantas submitted that the waiver extended to ‘associated material’ as discussed by Young J in AWB.
Justice Le Miere applied O’Callaghan J’s decision in Zantran, stating that ‘[t]he extent of any waiver is to be determined in accordance with the principles expounded in Mann v Carnell’ (at ). Accordingly, whilst Le Miere J noted that Perth Airport might be required to produce documents which are necessary to understand certain advice it received, this did not extend beyond the principles in Mann. For example, if Perth Airport had documents evidencing the knowledge and experience of Mr Houston (of Houston Kemp), it would not be inconsistent for Perth Airport to maintain confidentiality over those documents even though that knowledge and experience would no doubt underpin and influence the analysis he provided (at –).
In relation to any documents recording analysis undertaken by Dr Mundy, Le Miere J found that Perth Airport had not waived its privilege as it was not inconsistent for Perth Airport to state the Houston Kemp advice yet maintain confidentiality over the separate analysis by Dr Mundy (at ).
Together, Zantran and Perth Airport make it clear that the inconsistency principle from Mann is the sole principle relevant to determining whether legal professional privilege has been impliedly waived at common law. Whilst it may, in some instances, be inconsistent to retain confidentiality over certain documents associated with other waived communications, this will not always be so. Accordingly, Young J’s decision in AWB cannot be regarded as establishing a separate ‘associated material waiver’.