6. In Dasreef Pty Ltd v Hawchar (2011) 85 ALJR 694, the majority (French CJ, Gummow, Hayne, Crennan, Kiefel and Bell JJ) said at  that “the admissibility of opinion evidence is to be determined by application of the requirements of the Evidence Act rather than by any attempt to parse and analyse particular statements in decided cases divorced from the context in which those statements were made.
7. The question to which s 79(1) directs attention is, as I have said, whether the opinion is wholly or substantially based on specialised knowledge in turn based on training, study or experience. The threshold question is therefore whether the opinion is expressed in a way that makes it possible to answer the question. See Gleeson CJ in HG v the Queen (1999) 197 CLR at . His Honour’s observation was adopted by the majority in Dasreef at .
8. In the context of admissibility of opinion evidence, reference is often made to the analysis of Heydon JA in Makita (Australia) Pty Ltd v Sprowles (2001) 52 NSWLR 705.