admitting the evidence to determine whether the potential benefits justify the risks associated with its reception: White Burgess,
at paras. 19, 23-24; R. v. Abbey (2009), 97 O.R. (3d) 330, 
O.J. No. 3534, 2009 ONCA 624, at para. 76, leave to appeal to
S.C.C. refused  S.C.C.A. No. 125 (“Abbey ’09”).
 The requirements the proposed evidence must meet at the
threshold stage are familiar:
( i) relevance;
( ii) necessity in assisting the trier of fact;
( iii) the absence of an exclusionary rule; and
( iv) a properly qualified expert.
See White Burgess, at para. 19; R. v. Mohan,  2 S.C.R. 9,
 S.C.J. No. 36, at p. 20 S.C.R.
 At the threshold stage, relevance refers to logical relevance, the relationship between the evidence and the fact in
issue it is tendered to establish. Evidence is relevant where it
is probative of the fact its proponent seeks to establish by its
introduction: White Burgess, at para. 23; R. v. J. J. (J.-L.), 
2 S.C.R. 600,  S.C.J. No. 52, 2000 SCC 51, at para. 47;
Abbey ’09, at paras. 82, 84.
 To satisfy the necessity requirement at the threshold stage,
the proposed evidence must be more than helpful to the trier of
fact in its decision. A standard of “helpful” sets the bar for the
requirement of necessity too low. Although necessity is not to
be judged by too strict a standard, the proposed opinion must be
necessary in the sense that it provides information which is likely
to be outside the experience of the trier of fact. The evidence
must be necessary to enable the trier of fact to appreciate the
matters in issue because of their technical nature. Put in another
way, the subject matter of the inquiry must be such that ordinary
people are unlikely to form a correct judgment about it, if unassisted by persons with special knowledge: Mohan, at pp. 23-24
S.C.R.; Kelliher (Village) v. Smith,  S.C.R. 672,  S.C.J.
No. 47, at p. 684 S.C.R.; Abbey ’82, at p. 42 S.C.R.
 Like the requirement of relevance, the necessity of the proposed expert evidence is assessed in light of its potential to distort
the fact-finding process. If, on the proven facts, the trier of fact
can form their own conclusions without help, then the opinion of
the expert is unnecessary, its introduction apt to overwhelm the
trier of fact and distract them from their task: White Burgess, at
para. 21; Mohan, at p. 24 S.C.R.; R. v. Turner,  Q.B. 834,
 1 All E.R. 70, at p. 841 Q.B.; Abbey ’82, at p. 42 S.C.R.