before the hearing. If of a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject, the facts or data need not be admissible in evidence.

ELEMENTS

A.

B.

Facts or data supporting opinion of expert may be

1. Those perceived by the witness, or

2.

Made known at the hearing, including hypothetical questions.

Facts or data need not be admissible in evidence if

1. Of a type relied upon by experts in the field, and

This Rule follows the generally accepted practice of allowing the expert to express an opinion based upon data disclosed to him at or before the trial. The data, as the rule suggests, need not be admissible according to the traditional rules of evidence if experts in the field act or rely upon similar facts or data. For example, the physician in the field, and consequently the one on the witness stand, may rely upon a wide variety of information (reports of relatives, hospital technicians, statement by the patient, etc.) in forming a diagnosis. The evidence submitted at trial may not be ordinarily admissible; however, the physician on the witness stand is being asked to give the jury the benefit of his educated conclusion. ingly, he must give the jury the type of clinical opinion he is accustomed to forming and relying upon in the private practice of his profession. While his opinions may not be stated with mathematical precision, they are not hunches, suspicions or conjectures.

to the trier of fact.

Accord

Therefore, they are admissible as an aid

An expert witness may rely upon books, treatises, or records in forming

his opinion.

However, he must be able to produce the materials he relied

upon in court. See Rule 705. Additionally, the expert may give testimony based on his observations during a personal examination or based upon information provided by others. There is no requirement that the quantum of data or the source of the data conform to the generally accepted minimal standards within the field. Nor is there a requirement that the expert follow generally accepted procedures in conducting any experiments or tests relative to the problem in question. Any deficiencies in the foregoing areas merely go to the weight of the expert's testimony and not to its admissibility.

Rules 703 and 705 permit the expert to testify as to matters which would otherwise constitute hearsay for the purpose of illustrating the basis of his opinion.

Testimony in the form of an opinion or inference otherwise admissible is not objectionable because it embraces an ultimate issue to be decided by the trier of fact.

ELEMENTS

A. Expert may give opinion on ultimate issue if

1. Otherwise admissible and

2. Helpful to trier of fact.

COMMENTS

This Rule departs from the traditional line of cases which precluded the witness from giving an opinion which embraced the ultimate issue. This departure from the old rule was warranted inasmuch as the expert often was forced to address the ultimate issue in rendering an opinion. For example, a doctor must testify as to whether a surgeon's actions departed from the standard a reasonable physician would employ in a similar operation in order for the jury to determine whether he was negligent. However, all opinions which embrace the ultimate issue are not admissible under the Rule. Where the opinion is not based upon first hand knowledge or observation and the facts relative to the matter are fully within the competence of the jury to resolve, an expert witness should not be allowed to give an opinion on the ultimate issue.

ILLUSTRATION

Assume X, a coroner, is testifying at a civil proceeding in which the ultimate issue is whether Z committed suicide. The insurance carrier has raised suicide as an affirmative defense in order to avoid paying the insurance policy. X, in response to a question, testifies that, in his opinion, Z committed suicide. Y objects and moves to strike the answer as being inadmissible inasmuch as it is a legal conclusion embracing the ultimate issue, whether Z committed suicide. In this example, the court should sustain the objection and strike the answer.

Whenever a proffered opinion is phrased in legal terms and addresses the ultimate issue as a matter of law, it should be deemed inadmissible. For

example, X and Y cannot testify that they heard Z make obscene statements in violation of a statute which prohibits the use of obscene language, if they cannot recall what words Z had said. If they could recite what Z had said, it would still be within the competence of the trier of fact to determine whether the words were obscene. Furthermore, X and Y could not testify that the words were obscene in that the opinion would express a legal conclusion. The key to the application of Rule 704 is a determination that the opinion relates to matters within the witness' special competence and skill and not to matters of common knowledge and observation.

The expert may testify in terms of opinion or inference and give his reasons therefor without prior disclosure for the underlying facts or data, unless the court requires otherwise. The expert may in any event be required to disclose the underlying facts or data on cross-examination.

ELEMENTS

A. Expert may testify in terms of opinions and inferences

B. Expert may give reasons for his opinions

C.

Underlying data or facts need not be disclosed, except

COMMENTS

This rule allows the expert witness on direct examination to give his opinion and the reasons for the opinion without disclosing the facts upon which he based his opinion. This procedure has been criticized because it leaves to the cross-examiner the responsibility of demanding production of the materials or facts upon which the opinion is based. This criticism is often ignored inasmuch as if the underlying facts are impressive, the party calling the witness may disclose them. Moreover, the cross-examiner has the option of not asking the witness to disclose the basis for his opinion. Additionally, the proper use of discovery will allow counsel to ascertain what materials or facts the witness will rely upon in giving his expert opinion.

The Rule requires the witness to surrender upon demand the authorities upon which he bases his opinion. Accordingly, a witness may not mouth opinions without disclosing the basis for them. This permits the crossexaminer to scrutinize the supporting materials and determine whether they in fact support the opinion. The value of an expert's testimony rests upon the material from which his opinion is fashioned and the reasoning process by which he proceeds from his materials to his conclusions or opinion. The validity of the relationship between his opinion and his materials is for the trier of fact to decide.

The expert may be cross-examined as to his opinion by reference to other reputable works in his field. It is not necessary for the expert to have relied or based his opinion upon the particular authority the cross-examiner seeks to use to cross-examine him. It should be borne in mind that opinions