Qualified Expert Evidence: Difference between revisions

Revision as of 19:05, 2 November 2020

< Evidence
< Opinion Evidence

General Principles

Expert opinion is testimonial evidence that gives an opinion on facts perceived by him or another that concerns an issue that is likely outside the experience and knowledge of the trier-of-fact (i.e. a lay person). ^[1] The expert must have special knowledge in the matter ^[2] and the opinion must be reasonably necessary to assist the trier-of-fact to make a proper judgment. ^[3] There must also be no exclusionary rules that would otherwise prohibit the evidence from being given. ^[4]

Burden of Proof

The presumption for any given witness is that an opinion evidence is not admissible.^[5]

Specialized Knowledge Vs Expert Opinion

A person testifying to specialized to technical knowledge will not necessarily be required to be qualified as an expert. Where they testify to their "factual knowledge" based on their "knowledge, observations and experience".^[6]

It has been accepted that technical evidence describing the "general rule and its exceptions" of the functioning of complex systems is not opinion evidence where the "understand[ing] the scientific and technical underpinnings" are not necessary to give reliable descriptions.^[7]

An expert who testifies to direct observation without opinion is not subject to the opinion rule of exclusion. This evidence is admitted in the same way as eye-witness evidence.^[8]

The expert is not to testify to facts, but rather only opinion to allow the trier-of-fact to draw inferences. ^[9]

Relevance

Relevance is "a threshold requirement" to admitting expert evidence.^[10]

Specialization

The key requirement for expert evidence is that the expert "possesses special knowledge and experience going beyond that of the trier of fact".^[11] As long as the court is satisfied that the witness is sufficiently experienced he should be qualified.^[12]

Any deficiencies of the knowledge or opinion simply goes to weight.^[13]

The means by which the skill, expertise, or knowledge was acquired goes to weight and not admissibility.^[14] It is acceptable to obtain the ability to give an opinion from study, instruction, practical experience or observations. Formal study in not necessary.^[15]

Jury Instruction

Where a qualified expert gives opinion evidence outside of their field, the problem can generally be remedied through a "remedial instruction advising the jury to disabuse their minds of the inadmissible evidence".^[16]

Standard of Review

Trial judges are entitled to "wide discretion" and deference when weighing the costs and benefits of admitting expert evidence.^[17]

Whether someone can be qualified as an expert is a question of law and is reviewable on a standard of correctness.^[18]

↑ Folkes v Chadd (1782), 3 Dougl. 157
R v J-L J, [2000] 2 SCR 600, 2000 SCC 51 (CanLII), per Binnie J, at para 56
R v Abbey, 1982 CanLII 25 (SCC), [1982] 2 SCR 24, per Dickson J
R v Mohan, 1994 CanLII 80 (SCC), [1994] 2 SCR 9, per Sopinka J at 413 (the opinion must "provide information ‘which is likely to be outside the experience or knowledge of’” the trier of fact")
R v Bunniss (1964), 44 CR 262 (BC Co. Ct.), 1964 CanLII 673 (BC SC), per Tyrwhitt-Drake J (an expert is "one who has by dint of training and practice, acquired a good knowledge of the science or art concerning which his opinion is sought, and the practical ability to use his judgment in that science")
↑ R v Terceira, 1998 CanLII 2174 (ON CA), (1998) 123 CCC 1 (Ont. CA), per Finlayson JA Mohan, supra, at p. 414 (the witness must be “shown to have acquired special or peculiar knowledge through study or experience in respect of the matters on which he or she undertakes to testify”)
↑ Mohan, supra
R v Lovie, 1995 CanLII 801 (ON CA), per Finlayson JA
↑ R v NO, 2009 ABCA 75 (CanLII), per curiam, at para 19
↑ Abbott and Haliburton Company v WBLI Chartered Accountants, 2013 NSCA 66 (CanLII), per MacDonald CJ (dissenting on other issue), at para 24
↑ R v Hamilton, 2011 ONCA 399 (CanLII), per curiam, at paras 273 to 284 - evidence from phone company as to the mechanical workings of cell towers and their relationship to the cell phone
R v Ranger, 2010 ONCA 759 (CanLII), per curiam -- cell phone tower evidence
cf. R v Korski, 2009 MBCA 37 (CanLII), per Steel JA -- required expert to testify on cell tower evidence
R v Potter, 2020 NSCA 9 (CanLII), at paras 441 to 423
R v Ajise, 2018 ONCA 494 (CanLII), at para 23
R v MacDonald, 2020 NSCA 69 (CanLII), at para 58, per Derrick JA (“ Technical evidence grounded in experience, without more, does not constitute expert evidence.”)
↑ Hamilton, supra, at paras 273, 274, 277
↑ R v KA, 1999 CanLII 3793 (ON CA), per Charron JA, at para 72
↑ R v Parrott, 2001 SCC 3 (CanLII), [2001] 1 SCR 178, per Binnie J
R v Lavallee, 1990 CanLII 95 (SCC), [1990] 1 SCR 852, per Wilson J
↑ Mohan, supra, at p. 411
↑ R v Béland, 1987 CanLII 27 (SCC), [1987] 2 SCR 398, per McIntyre J, at p. 415
R v Marquard, 1993 CanLII 37 (SCC), [1993] 4 SCR 223, per McLachlin J, at para 35
R v Chan, 1993 ABCA 383 (CanLII), (1993), 145 A.R. 304, per curiam, at para 9
↑ Chan, ibid., at para 9
↑ Chan, ibid., at para 9
↑ Chan, ibid., at para 9 citing Sopinka, Lederman and Bryant, The Law of Evidence of Canada (1992), at pp. 536‑537: ("As long as the court is satisfied that the witness is sufficiently experienced in the subject matter at issue, the court will not be concerned with whether his or her skill was derived from specific studies or by practical training, although that may affect the weight to be given to the evidence.")
R v Rayner, 2000 NSCA 143 (CanLII), , 189 N.S.R. (2d) 144, per Saunders JA
↑ R v Melaragni, (1992), 73 CCC (3d) 348 (Ont. Ct. Gen. Div.), 1992 CanLII 12764 (ON SC), per Moldaver JA
R v NO, 2009 ABCA 75 (CanLII), per curiam, at para 22
↑ R v Sekhon, 2014 SCC 15 (CanLII), per Moldaver J, at para 48
↑ R v Clark, 2016 ABCA 72 (CanLII), per curiam, at paras 59 to 62
R v DD, 2000 SCC 43 (CanLII), per Major J, at para 13
R v Soni, 2016 ABCA 231 (CanLII), per curiam (2:1), at para 8
R v Dominic, 2016 ABCA 114 (CanLII), per curiam, at para 17
R v Abbey, 2009 ONCA 624 (CanLII), per Doherty JA, at para 97, leave to appeal to SCC refused
↑ R v Bear (C.W.), 2013 MBCA 96 (CanLII), per Steel JA, at para 81

Requirements of Expert Evidence ("Mohan" Test)

Legal Requirements for Qualified Expert Evidence

Procedure

Procedure for Calling Expert Evidence

Evidence

Rules of Evidence for a Qualified Expert

Example Fields of Qualifications

Established Fields of Expert Evidence

Opinion Evidence Outside of Qualification

Where a qualified expert testifies to matters directly outside of their area of qualification but is clearly within their area of special knowledge, the evidence can still be accepted absent any objection to the evidence by the opposing side.^[1] Likewise, a technical failure to qualify someone who clearly has expertise in the area, absent any objections, should be permitted to give expert evidence.^[2]

↑ R v Marquard, 1993 CanLII 37 (SCC), [1993] 4 SCR 223, per McLachlin J, at pp. 242-44
↑ Marquard, ibid., at pp. 242-44

Where Technical Evidence Does Not Require Expert Evidence

There is some difference in opinion of whether or not expert qualification is needed to present evidence from cell phone towers.^[1] It is generally accepted that even where it is not necessary, it is useful to explain some of the records.^[2]

Evidence on the regular functioning of social media websites can in circumstances be accepted without qualification.^[3]

↑ R v Hamilton, 2011 ONCA 399 (CanLII), per curiam, at paras 273 to 284 - evidence from phone company as to the mechanical workings of cell towers and their relationship to the cell phone. However, they did not give evidence triangulating the location of the accused's phone.
R v Ranger, 2010 ONCA 759 (CanLII), per curiam -- cell phone tower evidence accepted without qualification for general location evidence
cf. R v Korski, 2009 MBCA 37 (CanLII), per Steel JA -- required expert to testify on cell tower evidence
↑ e.g. R v McBean, 2011 ONSC 3125 (CanLII), per Fuerst J
↑ R v Soh, 2014 NBQB 20 (CanLII), per LaVigne J

Case Digests

Expert Evidence (Evidence Cases)

@@ Line 106: / Line 106: @@
 ==Evidence==
-Once the witness is qualified as an expert they are permitted to give evidence in the area for which they were qualified.
+* [[Rules of Evidence for a Qualified Expert]]
-; Requirement of Citing Sources
-The expert must cite the bases on his opinion in order for the trier-of-fact to evaluate the opinion.
-<ref>
-''R v Neil'', [http://canlii.ca/t/22tpj 1957 CanLII 70] (SCC), [1957] SCR 685{{Plurality}}<br>
-''R v Grandinetti'', [http://canlii.ca/t/4pvr 2003 ABCA 307] (CanLII){{perABCA|McFadyen JA}} (2:1)<br>
-''R v Trudel'', [http://canlii.ca/t/1p9ln 1994 CanLII 5397] (QC CA){{perQCCA|Brossard JA}}<br>
-</ref>
-The expert can use sources and information found in the "scope of his or her expertise"<ref>
-''R v SAB'', [http://canlii.ca/t/1g3m0 2003 SCC 60] (CanLII), [2003] 2 SCR 678{{perSCC|Arbour J}}{{atL|1g3m0|63}}</ref> as well as sources outside his knowledge in limited contexts.<ref>
-''R v Anderson'' (1914), 22 CCC 455, [http://canlii.ca/t/gcgg2 1914 CanLII 361] (AB CA){{perABCA|Harvey J}}<br>
-''R v Godfrey'', [http://canlii.ca/t/fp05t 1974 ALTASCAD 43] (CanLII), [1974] 4 W.W.R. 677, 18 CCC (2d) 90 (Alta. C.A.){{Plurality}} (2:1){{atps|102-104}}
-</ref>  The "second hand" evidence of texts is not admissible as evidence, but can be used to show the information on which the opinion is based.<ref>
-''R v Burns'', [http://canlii.ca/t/1frvk 1994 CanLII 127] (SCC), [1994] 1 SCR 656{{perSCC|McLachlin J}}</ref>
-; Questions on Reports, Texts, and Articles
-An expert may be cross-examined on a text, report or article relating to his area of expertise.
-<ref>
-''R c Taillefer'', [http://canlii.ca/t/1nk5h 1995 CanLII 4592] (QCCA){{perQCCA|Proulx JA}}<br>
-''R v Marquard'', [http://canlii.ca/t/1frx2 1993 CanLII 37] (SCC), [1993] 4 SCR 223{{perSCC|McLachlin J}}<br>
-</ref>
-The expert can only comment on works they are familiar with. If the expert acknowledges the authority, the examiner may read parts of the document to the witness to the extent that it is accepted as valid. Those confirmed passages will become evidence in the case<ref>
-{{ibid1|Marquard}} ("...in examining an expert witness on other expert opinions found in papers or books is to ask the witness if he or she knows the work.  If the answer is "no", or if the witness denies the work's authority, that is the end of the matter.  ...If the answer is "yes", and the witness acknowledges the work's authority, then the witness has confirmed it by the witness's own testimony. Parts of it may be read to the witness, and to the extent they are confirmed, they become evidence in the case.")<br>
-</ref>
-; Rejecting Uncontradicted Expert Evidence
-A judge may reject the uncontradicted expert evidence as unreasonable.
-<ref>
-''R v Prince'', (1971), 6 CCC (2d) 183 (Ont. C.A.), [http://canlii.ca/t/htwr4 1971 CanLII 1285] (ON CA){{perONCA|Gale CJ}}<br>
-''R v Lambkin'', [http://canlii.ca/t/5f67 2002 MBCA 157] (CanLII){{perMBCA|Monnin JA}}<br>
-</ref>
-The evidence should not be rejected if there is no contradictory evidence and the opinion is not seriously challenged.<ref>
-''R v Molodowic'', [http://canlii.ca/t/5262 2000 SCC 16] (CanLII), [2000] 1 SCR 420{{perSCC|Arbour J}}</ref>
-; Statistical and Annecdotal Evidence
-The expert cannot recite statistical evidence of probabilities based on prior similar events to infer what likely occurred in the incident at issue.<ref>
-''R v Klymchuk'' (2005), [http://canlii.ca/t/1m3d6 2005 CanLII 44167] (ON CA), 203 CCC (3d) 341 (Ont. C.A.){{perONCA|Doherty JA}}{{atL|1m3d6|46}}<br>
-''R v Shafia'', [http://canlii.ca/t/gvdw4 2016 ONCA 812] (CanLII){{perONCA|Watt JA}}{{AtL|gvdw4|242}} ("An expert is not entitled to give statistical evidence of probabilities based on prior similar events to support a conclusion about what happened on the occasion that forms the subject-matter of charges")<br>
-</ref>
-The expert may not give anecdotal evidence concerning prior similar events to suggest an opinion about the event at issue.<ref>
-{{ibid1|Shafia}}{{AtL|gvdw4|243}} ("Experts may not give anecdotal evidence gathered from prior experiences in proffering their opinion about conduct on a particular occasion. The evidence lacks legal relevance and is apt to engender significant prejudice, especially when adduced to rebut a defence")<br>
-''R v Sekhon'', [http://canlii.ca/t/g35qf 2014 SCC 15] (CanLII){{perSCC|Moldaver J}}{{atsL|g35qf|49| to 50}}
-</ref>
-; Area of Expertise
-The qualified "area of expertise" does not need to articulate the exact subject matter to which they will give evidence. It often sufficient to articulate the general area of knowledge.<ref>
-e.g. ''R v Rothgordt'', [http://canlii.ca/t/h494z 2017 BCCA 230] (CanLII){{perBCCA|Frankel JA}}{{atL|h494z|16}}<br></ref>
-; Use of Report
-It is common-place that an expert may testify with their reports on hand and may refer to them during testimony.<ref>
-''R v Sandham'', [2009] OJ No 4517 (Ont. S.C.J.), [http://canlii.ca/t/26cvj 2009 CanLII 58982] (ON SC){{perONSC|Heeney J}} ("Experts are routinely permitted to have their reports in front of them as they testify, and to refer to them as they deliver their evidence. Such reports are frequently entered as exhibits.")<br>
-</ref>
-There is some division of whether an expert report should be filed as an exhibit.<ref>
-''R v Millard and Smich'', [http://canlii.ca/t/gs46s 2016 ONSC 1517] (CanLII){{perONSC|Goodman J}} (" Generally speaking, I agree that experts’ reports, per se, ought not to be filed as exhibits.  The evidence is their “in-court” testimony. ")<br>
-</ref>
-{{reflist|2}}
-===Weight of Opinion===
-Expert opinion on anything that is not necessary for the trier-of-fact to make findings is not admissible.<ref>
-''R v Howard'', [http://canlii.ca/t/1ft53 1989 CanLII 99] (SCC), [1989] 1 SCR 1337{{perSCC|Lamer J}}<br>
-''R v Béland'', [http://canlii.ca/t/1ftm1 1987 CanLII 27] (SCC), [1987] 2 SCR 398{{perSCC|McIntyre J}}
-''R v Millar'', (1989), 49 CCC (3d) 193 (ONCA), [http://canlii.ca/t/gb34s 1989 CanLII 7151] (ON CA){{perONCA|Morden JA}}, at 220<br>
-</ref>
-The opinion evidence given must be within the qualified field of expertise.<ref>
-{{supra1|Howard}}<br>
-{{supra1|Millar}} <br>
-</ref>
-The expert need not have personal knowledge of any facts to give an opinion.<ref>
-''R v Preeper and Doyle'', [http://canlii.ca/t/ggx87 1888 CanLII 56] (SCC), (1888), 15 SCR 401{{Plurality}}
-</ref>
-A jury must be instructed that the hearsay evidence of the facts underlying the experts opinion is not admissible for any purpose other than to evaluate the weight of the opinion.<ref>
-''R v Babcock'', [http://canlii.ca/t/2dgrk 1984 ABCA 291] (CanLII){{perABCA|Moir JA}}
-</ref>
-The weight given to an opinion is a question of fact.<ref>
-''R v Smithers'', [http://canlii.ca/t/1mk9r 1977 CanLII 7] (SCC), [1978] 1 SCR 506{{perSCC|Dickson J}}
-</ref>
-The opinion must be specific to the case and not simply in generalities.<ref>
-''R v Li'', [http://canlii.ca/t/23m2k 1980 CanLII 344] (BC SC){{perBCSC|Trainor J}}
-</ref>
-; Requirements for a Factual Foundation
-Before a judge can rely upon an expert opinion, the expert must give evidence on the factual foundation relied upon to form the opinion.<ref>
-''R v Neil'', [http://canlii.ca/t/22tpj 1957 CanLII 70] (SCC), [1957] SCR 685{{Plurality}}<br>
-''R v Dietrich'', [http://canlii.ca/t/g1bt2 1970 CanLII 377] (ON CA){{perONCA|Gale CJ}}<br>
-</ref>
-Where the underlying facts are not established in evidence, the judge cannot rely upon the opinion.<ref>
-''R v Abbey'', [http://canlii.ca/t/1lpcd 1982 CanLII 25] (SCC), [1982] 2 SCR 24{{perSCC|Dickson J}} ("Before any weight can be given to an expert's opinion, the facts upon which the opinion is based must be found to exist.")<br>
-''R v Morgentaler'' (No. 2) (1973), 14 CCC (2d) 450 (Que. S.C.), [http://canlii.ca/t/htxsb 1973 CanLII 1462] (QC CQ){{perQCCQ|Hugessen ACJ}}
-''R v Lupien'', [1970] SCR 263, [http://canlii.ca/t/1xd5k 1969 CanLII 55] (SCC){{Plurality}}<br>
-{{supra1|Howard}}<br>
-''R v Phillion'', [http://canlii.ca/t/1tx3f 1977 CanLII 23] (SCC), [1978] 1 SCR 18{{perSCC|Ritchie J}}<br>
-</ref>
-The evidence relied upon for the opinion can include second-hand evidence, but that the it may affect the weight accorded to the opinion.<ref>
-''R v Alcantara'', [http://canlii.ca/t/fqvvj 2012 ABQB 225] (CanLII){{perABQB|Greckol J}}{{atL|fqvvj|125}}<br>
-</ref>
-; Evaluating Conflicting Expert Evidence
-Where the evidence of multiple experts conflict, it is not a matter of chosing one expert over the other, but rather giving weight to each expert and review the opinions as a whole.<ref>
-''R v Jonkman'', [http://canlii.ca/t/fvfwq 2012 SKQB 511] (CanLII){{perSKQB|Schwann J}}{{atL|fvfwq|97}}<br>
-Toneguzza-Norvell v Burnaby Hospital, [http://canlii.ca/t/1frwb 1994 CanLII 106] (SCC), [1994] 1 SCR 114{{perSCC|McLachlin J}}<br>
-''Housen v Nikulaison'', [http://canlii.ca/t/51tl 2002 SCC 33] (CanLII), [2002] 2 SCR 235{{perSCC|Iacobucci and Major JJ}}<br>
-</ref>
-; Evaluating Expert Evidence Without A Conflicting Evidence
-A judge need not believe or make any findings of fact based on the testimony of an expert witness due to the failure of the other side to adduce contradicting evidence.<ref>
-''R v Doodnaught'', [http://canlii.ca/t/h6m5m 2017 ONCA 781] (CanLII){{perONCA|Watt JA}}{{atL|h6m5m|124}} ("...as with the testimony of any witness, a trial judge need not believe or make findings of fact based on the testimony of an expert witness simply because no witness is called by the opposite party or evidence adduced to contradict it")<br>
-''R v Moke'' (1917), [http://canlii.ca/t/gw70b 1917 CanLII 426] (AB CA), 28 CCC 296 (Alta. S.C., A.D.){{perABCA|Walsh J}}{{atp|300}}<br>
-</ref>
-{{reflist|2}}
-===Hypothetical Questions===
-The opinion evidence can be related by way of hypothetical questions put to the expert.<ref>
-''R v Fiqia'', [http://canlii.ca/t/2dbft 1994 ABCA 402] (CanLII), (1994) 162 A.R. 117 (C.A.){{perABCA|Hunt JA}}</ref>
-However, the testimony cannot be "oath-helping" evidence.<ref>
-''R v Reid'', [http://canlii.ca/t/6g6g 2003 CanLII 14779] (ON C.A.){{perONCA|Moldaver JA}}</ref>
-The hypotheticals can be put to the expert where the facts are not in dispute.<ref>
-''R v Bleta'', [http://canlii.ca/t/1tvsq 1964 CanLII 14] (SCC), [1964] SCR 561{{perSCC|Ritchie J}}</ref>  If the underlying facts are in dispute the opinion cannot remove the fact-finding function of the trier-of-fact.<ref>
-''R v PG'', [http://canlii.ca/t/224d8 2009 ONCA 32] (CanLII){{perONCA|Juriansz JA}}</ref>
-The cross-examiner can put to the expert any proven or provable facts to determine whether it alters the confidence of the opinion.<ref>
-''R v Kerr'', [http://canlii.ca/t/533d 2000 BCCA 209] (CanLII){{perBCCA|McEachern CJ}}</ref>
-It can be preferrable to ask questions in hypothetical form on contradictory matters in order to avoid overly influencing the jury's fact-finding process.<ref>
-''R v Leinen'', [http://canlii.ca/t/g01l8 2013 ABCA 283] (CanLII){{perABCA|Hunt JA}} (2:1)
-</ref>
-The party seeking to rely on an expert opinion based on a hypothetical fact has the burden of establishing those underlying facts.<ref>
-''R v Lavallee'', [1990] 1 SCR 852, [http://canlii.ca/t/1fsx3 1990 CanLII 95] (SCC){{perSCC|Wilson J}}<br>
-''R v Flight'', [http://canlii.ca/t/g711g 2014 ABCA 185] (CanLII){{perABCA|Veldhuis JA}}<br>
-</ref>
-{{reflist|2}}
-===Ultimate Issue Rule===
-An expert should generally not give an opinion on an "ultimate issue" to the case otherwise the expert would usurp the role of the trier-of-fact.<ref>
-''R v Béland'', [http://canlii.ca/t/1ftm1 1987 CanLII 27] (SCC), [1987] 2 SCR 398{{perSCC|McIntyre J}}
-</ref>
-This is not a strict rule as it should be determined on a case-by-case.<ref>
-''R v Potts'', [http://canlii.ca/t/hr64n 2018 ONCA 294] (CanLII){{TheCourtONCA}}{{atL|hr64n|47}} ("It is worth recalling that no general rule precludes the introduction of expert opinion evidence on the ultimate issue in a criminal trial")<br>
-''R v Mohan'', [http://canlii.ca/t/1frt1 1994 CanLII 80] (SCC), [1994] 2 SCR 9{{perSCC|Sopinka J}}{{atps|24-25}}<br>
-''R v Bryan'' (2003), [http://canlii.ca/t/6xxg 2003 CanLII 24337] (ON CA), 175 CCC (3d) 285 (Ont. C.A.){{perONCA|Goudge JA}}{{atsL|6xxg|16| to 17}}<br>
-''R v Lucas'', [http://canlii.ca/t/g84mv 2014 ONCA 561] (CanLII), 121 O.R. (3d) 303{{TheCourtONCA}}{{atL|g84mv|271}}<br>
-</ref>
-Where the facts are not in dispute there is a discretion for the judge to allow the expert to give evidence on the ultimate issue.<ref>
-''Swietlinski v R'', [http://canlii.ca/t/1vm6l 1978 CanLII 56] (ON CA){{perONCA|Martin JA}}
-</ref>
-A psychologist has been allowed to give evidence on whether a murder was "planned and deliberate".<ref>
-''R v More'', [http://canlii.ca/t/22vz3 1963 CanLII 79] (SCC), [1963] SCR 522{{perSCC|Cartwright J}}
-</ref>
-Also whether the accused's condition is a "disease of the mind".<ref>
-''R v Cooper'', [http://canlii.ca/t/1tx9m 1979 CanLII 63] (SCC), [1980] 1 SCR 1149{{perSCC|Dickson J}}
-</ref>
-{{reflist|2}}
-===Change of Opinion===
-It is accepted that the testimony of witnesses, expert or otherwise, may change over time for various reasons. A mistrial would likely not be available where a witness gives advance notice that their evidence has changed.<ref>
-{{CanLIIR|Chen|j0dx2|2019 ONSC 3088 (CanLII)}}{{AtL|j0dx2|22}} ("Given this undeniable reality in criminal trials, it is difficult to imagine circumstances where it would be necessary to declare a mistrial simply because a witness gave advance notice to the lawyer who was planning on calling them, that they were going to, in fact, give unanticipated testimony at variance with some earlier indication of what their testimony might be.")
-</ref>
-{{reflist|2}}
-===Specific Types of Expert===
-; Drug Expert
-A lay person such as an RCMP officer cannot be a reliable expert simply by "conducting numerous casual conversations with drug users or traffickers."  This sort of "[a]necdotal evidence cannot be tested or verified hearsay must be supplemented and supported by some form of admissible evidence."<ref>
-''R v Klassen'', [http://canlii.ca/t/26j 2003 MBQB 253] (CanLII), [2003] M.J. No. 417{{perMBQB|Scurfield J}}</ref>
-{{Reflist|2}}
 ==Example Fields of Qualifications==