George Nassour v Anthony Mark Malouf t/as Malouf Solicitors  NSWSC 356. Harrison AsJ.
A Separate Doctrine of Waiver
105 Many authors have commented on the looseness with which the term "waiver" is used, further contributing to its already unsettled, inconsistent and "imprecise" meaning: Carter et al, Contract Law in Australia , 5th ed (2007) Lexis Nexis at 166; Paterson et al, Principles of Contract Law, 3rd ed (2009) Thomson Reuters, at 368; Commonwealth v Verwayen (1990) 170 CLR 394 at 406.
As Paterson et al observe (at 368), "often arguments framed in terms of waiver are actually, in substance, claims of election or estoppel, some judges nevertheless continue to analyse election or estoppel arguments using the language of waiver."
106 By contrast though, "Others appear to view the terms election and waiver as interchangeable": Principles &c, above, at 368. The authors cite two decisions in support of this observation.
The first is articulated by Keane JA (as he then was) in Kostopoulos v G E Commercial Finance  QCA 311 where his Honour said at  - :
"It is enough to say that, if it is correct that '... the primary meaning of the word waiver in legal parlance is the abandonment of a right in such a way that the other party is entitled to plead the abandonment by way of confession and avoidance if the right is thereafter asserted', then what is sometimes termed a 'waiver' must usually, in the absence of a new agreement between the parties, refer to what is, in substance, either election or estoppel. ... This is especially so in a contractual context."
107 The second can be gleaned from the decision of Waterman v Gerling Australia Insurance Co Pty Ltd (2005) 65 NSWLR 301 where Brereton J said at 320:
"Election, or waiver, is a principle under which one party, by electing to pursue a right which arises from breach or non-compliance by the other, may deprive itself of another right inconsistent with that election."
108 While submitting that Mr Malouf has waived his right to costs and disbursements by estoppel, Mr Nassour agitated another category of waiver separate from those enunciated by Keane JA and Brereton J.
Mr Nassour has submitted at paragraphs 40 to 44 of his amended submissions that waiver may exist as an independent doctrine separately applied from election and estoppel.
Mr Nassour refers to this independent doctrine in terms of a residual category of manifest unfairness at common law. Support for this third category of waiver has mixed support in recent case law.