
Opinion Evidence - Form of expert opinion
Unless the court orders otherwise, questions calling for the opinion of an expert witness need not be hypothetical in form, and the witness may state his opinion and reasons without first specifying the data upon which it is based. Upon cross-examination, he may be required to specify the data and other criteria supporting the opinion.[1]
The best method to follow is to have the witness first set forth all of the data upon which his opinion is based and the reasons for his opinion.
Questions calling for the opinion of an expert witness need not be hypothetical in form.[2] The expression of the expert’s opinion need not follow any particular form of words. What is required is testimony reflecting that the opinion is not based on supposition or speculation.[3]
As a general rule, an expert opinion must be based upon facts disclosed by the evidence or known by the witness personally.[4]
An expert may not reach a conclusion by assuming material facts not supported by the evidence and may not guess or speculate in drawing a conclusion.[5]
Where an expert bases the opinion upon facts which are within the expert’s personal knowledge but which are not yet in the record, the expert must testify as to those facts before the opinion is received in evidence.[6]
An expert witness may state the opinion and reasons for it without first specifying the technical data upon which the opinion is based, leaving the development of that data to cross-examination.[7] However, Civil Practice Law and Rules § 4515 does not change the basic principle that an expert's opinion not based on facts is "worthless.” [8]
Expert testimony should generally be excluded where the opinion is based upon facts not fairly inferable from the evidence.[9]
However, an expert may base an opinion on circumstantial evidence, with the lack of direct evidence simply affecting the weight of the opinion.[10] The general principle is subject to two narrow exceptions. An expert may testify to an opinion based on material not in evidence if the material “is of a kind accepted in the profession as reliable in forming a professional opinion” or the material "comes from a witness subject to full cross-examination on the trial.[11]
To summarize, an expert's testimony may be based on any one or a combination of evidence in the record, [12] or facts personally known to the expert, [13] or "professionally reliable" material not included in evidence in the record or facts personally known to the expert; or other information derived from a witness subject to cross-examination at trial.[14]
If an expert's testimony is to be based upon "professionally reliable" sources, his attorney must be prepared to satisfy the trial judge that the information to be used by the witness meets the test of' being "accepted in the profession as reliable”. Reliability can be established at a preliminary hearing by testimony, [15] or by reference to the available literature on the subject,[16] or by judicial notice. The test of reliability ““is not whether a particular procedure is unanimously endorsed by the scientific community, but whether it is generally accepted as reliable."[17]
If an opinion is given and cross-examination reveals it to be based on facts not in evidence, the opinion should be stricken. [18]
An expert may base an opinion upon facts which are judicially noticed, provided that adequate and timely opportunity is provided to adverse parties to challenge the applicability of judicial notice and to cross-examine the expert as to the opinion.[19]
An expert may not give an opinion as to dollar value of a tort action.[20]
[1] New York Civil Practice Law and Rules § 4515.
[2] New York Civil Practice Law and Rules § 4515.
[3] Matott v Ward, 48 NY2d 455, 423 NYS2d 645, 399 NE2d 532
[4] Sawyer v Dreis & Krump Mfg. Co., 67 NY2d 328, 502 NYS2d 696, 493 NE2d 920; Hambsch v New York City Transit Authority, 63 NY2d 723, 480 NYS2d 195, 469 NE2d 516; Cassano v Hagstrom, 5 NY2d 643, 187 NYS2d 1, 159 NE2d 348; Nyon Sook Lee v Shields, 188 AD2d 637, 591 NYS2d 522; Tucker v Elimelech, 184 AD2d 636, 584 NYS2d 895; Hugelmaier v Sweden, 144 AD2d 934, 534 NYS2d 253; De Tommaso v M. J. Fitzgerald Constr. Corp., 138 AD2d 341, 525 NYS2d 632; Reynolds v A. C. Towne Corp., 132 AD2d 952, 518 NYS2d 528; Stringile v Rothman, 142 AD2d 637, 530 NYS2d 838.
[5] Quinn v Artcraft Constr., 203 AD2d 444, 610 NYS2d 598; see Wright v New York City Housing Authority, 208 AD2d 327, 624 NYS2d 144 (expert may not create facts upon which conclusion is based); Semans v Semans (1993, 3d Dept) 199 AD2d 790, 605 NYS2d 510, app den 83 NY2d 758, 615 NYS2d 875, 639 NE2d 416.
[6] People v Jones, 73 NY2d 427, 541 NYS2d 340, 539 NE2d 96.
[7] CPLR 4515; see Romano v Stanley, 90 NY2d 444, 661 NYS2d 589, 684 NE2d 19; Tarlowe v Metropolitan Ski Slopes, Inc., 28 NY2d 410, 322 NYS2d 665, 271 NE2d 515.
[8] Caton v Doug Urban Constr. Co., 65 NY2d 909, 493 NYS2d 453, 483 NE2d 128; see People v Jones, 73 NY2d 427, 541 NYS2d 340, 539 NE2d 96.
[9] See Tarlowe v Metropolitan Ski Slopes, Inc., 28 NY2d 410, 322 NYS2d 665, 271 NE2d 515; Wheaton v Guthrie, 89 AD2d 809, 453 NYS2d 480.
[10] Soulier v Hughes, 119 AD2d 951, 501 NYS2d 480.
[11] People v Sugden, 35 NY2d 453, 363 NYS2d 923, 323 NE2d 169; Natale v Niagara Mohawk Power Corp., 135 AD2d 955, 522 NYS2d 364; see People v Angelo, 88 NY2d 217, 644 NYS2d 460, 666 NE2d 1333; People v Stone, 35 NY2d 69, 358 NYS2d 737, 315 NE2d 787 (psychiatrist may testify as to opinion with respect to a person's sanity and may indicate that opinion is based, in part, upon extrajudicial statements of others associated with the person); but see People v Ricco, 56 NY2d 320, 452 NYS2d 340, 437 NE2d 1097 (psychiatrist improperly permitted to state opinion as to a person's sanity where the only basis for such opinion was a police detective's testimony); People v Wilson, 133 AD2d 179, 518 NYS2d 690 (error to allow psychologist to give opinion as to defendant's mental capacity based on expert's courtroom observations of defendant where no evidence of the scientific acceptance of the reliability of this procedure was presented).
[12] Cassano v. Hagstrom, 5 N.Y.2d 643, 187 N.Y.S.2d 1 (1959).
[13] Aetna Casualty & Surety Co. v. Barile, 86 A.D.2d 362, 450 N.Y.S.2d 10.
[14] Hambsch v New York City Transit Authority, 63 N.Y.2d 723, 480 N.Y.S. 2d 195, 469 N.E.2d 516 (1984) characterized the last two items as "two limited exceptions" to the general rule, represented by evidence in the record and facts reasonably known to the expert.
People v. Sugden, 35 N.Y.2d 453, 363 N.Y.S.2d 923, 323 N.E.2d 169 (1974) allowed the expert to "rely on material, which ... does not qualify under the professional test [but] comes from a witness subject to full cross-examination on the trial."
People v. Stone, 35 N.Y.2d 69, 76, 358 N.Y.S.2d 737, 315 N.E.2d 787 (1974) held that "In evaluating the worth of [an expert's] opinion, the jury should be informed of his sources and how he evaluated those sources.... on cross-examination, the validity of his reasoning process may be probed-and any 'shaky factual basis' of the opinion exposed... The jury may then take -the opinion for what the think it is worth.”
Standard of Helpfulness - The guiding principle is that expert opinion is proper when it would help to clarify an issue calling for professional or technical knowledge, possessed by the expert and beyond the ken of the typical juror. DeLong v County of Erie, 60 N.Y.2d 296. See also People v. Cronin, 60 N.Y.2d 430, 470 N.Y.S.2d 110.
[15] People v. De Zinn, 112 Misc.2d 753, 447 N.Y.S.2d 585 (Co. Ct. Tompkins, 1981)
[16] See People v. Middleton, 54 N.Y.2d 42, 49, 444 N.Y.S.2d 581, 429 N.E.2d 100 (1981).
[17] People v Middleton, 54 N.Y.2d at 49.
[18] Lopato v. Kinney Rent-A-Car, 73 A.D.2d 565, 423 N-Y.S.2d 42 (1 Dept., 1979).
O’Shea v. Sarre, 106 A.D.2d 435, 482 N.Y.S.2d 529 (2d Dept., 1984) held that it was improper for an expert witness to base his testimony on the opinions of other colleagues who are not called as witnesses at trial.
[19] People v Jones, 73 NY2d 427, 541 NYS2d 340, 539 NE2d 96.
[20] Kulak v Nationwide Mut. Ins. Co., 40 NY2d 140, 386 NYS2d 87, 351 NE2d 735.
Unless the court orders otherwise, questions calling for the opinion of an expert witness need not be hypothetical in form, and the witness may state his opinion and reasons without first specifying the data upon which it is based. Upon cross-examination, he may be required to specify the data and other criteria supporting the opinion.[1]
The best method to follow is to have the witness first set forth all of the data upon which his opinion is based and the reasons for his opinion.
Questions calling for the opinion of an expert witness need not be hypothetical in form.[2] The expression of the expert’s opinion need not follow any particular form of words. What is required is testimony reflecting that the opinion is not based on supposition or speculation.[3]
As a general rule, an expert opinion must be based upon facts disclosed by the evidence or known by the witness personally.[4]
An expert may not reach a conclusion by assuming material facts not supported by the evidence and may not guess or speculate in drawing a conclusion.[5]
Where an expert bases the opinion upon facts which are within the expert’s personal knowledge but which are not yet in the record, the expert must testify as to those facts before the opinion is received in evidence.[6]
An expert witness may state the opinion and reasons for it without first specifying the technical data upon which the opinion is based, leaving the development of that data to cross-examination.[7] However, Civil Practice Law and Rules § 4515 does not change the basic principle that an expert's opinion not based on facts is "worthless.” [8]
Expert testimony should generally be excluded where the opinion is based upon facts not fairly inferable from the evidence.[9]
However, an expert may base an opinion on circumstantial evidence, with the lack of direct evidence simply affecting the weight of the opinion.[10] The general principle is subject to two narrow exceptions. An expert may testify to an opinion based on material not in evidence if the material “is of a kind accepted in the profession as reliable in forming a professional opinion” or the material "comes from a witness subject to full cross-examination on the trial.[11]
To summarize, an expert's testimony may be based on any one or a combination of evidence in the record, [12] or facts personally known to the expert, [13] or "professionally reliable" material not included in evidence in the record or facts personally known to the expert; or other information derived from a witness subject to cross-examination at trial.[14]
If an expert's testimony is to be based upon "professionally reliable" sources, his attorney must be prepared to satisfy the trial judge that the information to be used by the witness meets the test of' being "accepted in the profession as reliable”. Reliability can be established at a preliminary hearing by testimony, [15] or by reference to the available literature on the subject,[16] or by judicial notice. The test of reliability ““is not whether a particular procedure is unanimously endorsed by the scientific community, but whether it is generally accepted as reliable."[17]
If an opinion is given and cross-examination reveals it to be based on facts not in evidence, the opinion should be stricken. [18]
An expert may base an opinion upon facts which are judicially noticed, provided that adequate and timely opportunity is provided to adverse parties to challenge the applicability of judicial notice and to cross-examine the expert as to the opinion.[19]
An expert may not give an opinion as to dollar value of a tort action.[20]
[1] New York Civil Practice Law and Rules § 4515.
[2] New York Civil Practice Law and Rules § 4515.
[3] Matott v Ward, 48 NY2d 455, 423 NYS2d 645, 399 NE2d 532
[4] Sawyer v Dreis & Krump Mfg. Co., 67 NY2d 328, 502 NYS2d 696, 493 NE2d 920; Hambsch v New York City Transit Authority, 63 NY2d 723, 480 NYS2d 195, 469 NE2d 516; Cassano v Hagstrom, 5 NY2d 643, 187 NYS2d 1, 159 NE2d 348; Nyon Sook Lee v Shields, 188 AD2d 637, 591 NYS2d 522; Tucker v Elimelech, 184 AD2d 636, 584 NYS2d 895; Hugelmaier v Sweden, 144 AD2d 934, 534 NYS2d 253; De Tommaso v M. J. Fitzgerald Constr. Corp., 138 AD2d 341, 525 NYS2d 632; Reynolds v A. C. Towne Corp., 132 AD2d 952, 518 NYS2d 528; Stringile v Rothman, 142 AD2d 637, 530 NYS2d 838.
[5] Quinn v Artcraft Constr., 203 AD2d 444, 610 NYS2d 598; see Wright v New York City Housing Authority, 208 AD2d 327, 624 NYS2d 144 (expert may not create facts upon which conclusion is based); Semans v Semans (1993, 3d Dept) 199 AD2d 790, 605 NYS2d 510, app den 83 NY2d 758, 615 NYS2d 875, 639 NE2d 416.
[6] People v Jones, 73 NY2d 427, 541 NYS2d 340, 539 NE2d 96.
[7] CPLR 4515; see Romano v Stanley, 90 NY2d 444, 661 NYS2d 589, 684 NE2d 19; Tarlowe v Metropolitan Ski Slopes, Inc., 28 NY2d 410, 322 NYS2d 665, 271 NE2d 515.
[8] Caton v Doug Urban Constr. Co., 65 NY2d 909, 493 NYS2d 453, 483 NE2d 128; see People v Jones, 73 NY2d 427, 541 NYS2d 340, 539 NE2d 96.
[9] See Tarlowe v Metropolitan Ski Slopes, Inc., 28 NY2d 410, 322 NYS2d 665, 271 NE2d 515; Wheaton v Guthrie, 89 AD2d 809, 453 NYS2d 480.
[10] Soulier v Hughes, 119 AD2d 951, 501 NYS2d 480.
[11] People v Sugden, 35 NY2d 453, 363 NYS2d 923, 323 NE2d 169; Natale v Niagara Mohawk Power Corp., 135 AD2d 955, 522 NYS2d 364; see People v Angelo, 88 NY2d 217, 644 NYS2d 460, 666 NE2d 1333; People v Stone, 35 NY2d 69, 358 NYS2d 737, 315 NE2d 787 (psychiatrist may testify as to opinion with respect to a person's sanity and may indicate that opinion is based, in part, upon extrajudicial statements of others associated with the person); but see People v Ricco, 56 NY2d 320, 452 NYS2d 340, 437 NE2d 1097 (psychiatrist improperly permitted to state opinion as to a person's sanity where the only basis for such opinion was a police detective's testimony); People v Wilson, 133 AD2d 179, 518 NYS2d 690 (error to allow psychologist to give opinion as to defendant's mental capacity based on expert's courtroom observations of defendant where no evidence of the scientific acceptance of the reliability of this procedure was presented).
[12] Cassano v. Hagstrom, 5 N.Y.2d 643, 187 N.Y.S.2d 1 (1959).
[13] Aetna Casualty & Surety Co. v. Barile, 86 A.D.2d 362, 450 N.Y.S.2d 10.
[14] Hambsch v New York City Transit Authority, 63 N.Y.2d 723, 480 N.Y.S. 2d 195, 469 N.E.2d 516 (1984) characterized the last two items as "two limited exceptions" to the general rule, represented by evidence in the record and facts reasonably known to the expert.
People v. Sugden, 35 N.Y.2d 453, 363 N.Y.S.2d 923, 323 N.E.2d 169 (1974) allowed the expert to "rely on material, which ... does not qualify under the professional test [but] comes from a witness subject to full cross-examination on the trial."
People v. Stone, 35 N.Y.2d 69, 76, 358 N.Y.S.2d 737, 315 N.E.2d 787 (1974) held that "In evaluating the worth of [an expert's] opinion, the jury should be informed of his sources and how he evaluated those sources.... on cross-examination, the validity of his reasoning process may be probed-and any 'shaky factual basis' of the opinion exposed... The jury may then take -the opinion for what the think it is worth.”
Standard of Helpfulness - The guiding principle is that expert opinion is proper when it would help to clarify an issue calling for professional or technical knowledge, possessed by the expert and beyond the ken of the typical juror. DeLong v County of Erie, 60 N.Y.2d 296. See also People v. Cronin, 60 N.Y.2d 430, 470 N.Y.S.2d 110.
[15] People v. De Zinn, 112 Misc.2d 753, 447 N.Y.S.2d 585 (Co. Ct. Tompkins, 1981)
[16] See People v. Middleton, 54 N.Y.2d 42, 49, 444 N.Y.S.2d 581, 429 N.E.2d 100 (1981).
[17] People v Middleton, 54 N.Y.2d at 49.
[18] Lopato v. Kinney Rent-A-Car, 73 A.D.2d 565, 423 N-Y.S.2d 42 (1 Dept., 1979).
O’Shea v. Sarre, 106 A.D.2d 435, 482 N.Y.S.2d 529 (2d Dept., 1984) held that it was improper for an expert witness to base his testimony on the opinions of other colleagues who are not called as witnesses at trial.
[19] People v Jones, 73 NY2d 427, 541 NYS2d 340, 539 NE2d 96.
[20] Kulak v Nationwide Mut. Ins. Co., 40 NY2d 140, 386 NYS2d 87, 351 NE2d 735.
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