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Federal Rules of Evidence – Rule 705 

(through July 14, 2022)

Crushed Rule

Experts may give their opinion without disclosing relied-upon info. But they may have to disclose that info on cross.

Actual Rule

Unless the court orders otherwise, an expert may state an opinion — and give the reasons for it — without first testifying to the underlying facts or data. But the expert may be required to disclose those facts or data on cross-examination.

Selected Committee Notes 

The hypothetical question has been the target of a great deal of criticism as encouraging partisan bias, affording an opportunity for summing up in the middle of the case, and as complex and time consuming. Ladd, Expert Testimony, 5 Vand.L.Rev. 414, 426–427 (1952). While the rule allows counsel to make disclosure of the underlying facts or data as a preliminary to the giving of an expert opinion, if he chooses, the instances in which he is required to do so are reduced. This is true whether the expert bases his opinion on data furnished him at secondhand or observed by him at firsthand.

The elimination of the requirement of preliminary disclosure at the trial of underlying facts or data has a long background of support. In 1937 the Commissioners on Uniform State Laws incorporated a provision to this effect in the Model Expert Testimony Act, which furnished the basis for Uniform Rules 57 and 58. Rule 4515, N.Y. CPLR (McKinney 1963), provides:

“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 * * *,”

If the objection is made that leaving it to the cross-examiner to bring out the supporting data is essentially unfair, the answer is that he is under no compulsion to bring out any facts or data except those unfavorable to the opinion. The answer assumes that the cross-examiner has the advance knowledge which is essential for effective cross-examination. This advance knowledge has been afforded, though imperfectly, by the traditional foundation requirement. Rule 26(b)(4) of the Rules of Civil Procedure, as revised, provides for substantial discovery in this area, obviating in large measure the obstacles which have been raised in some instances to discovery of findings, underlying data, and even the identity of the experts. Friedenthal, Discovery and Use of an Adverse Party’s Expert Information, 14 Stan.L.Rev. 455 (1962).

These safeguards are reinforced by the discretionary power of the judge to require preliminary disclosure in any event.

This rule, which relates to the manner of presenting testimony at trial, is revised to avoid an arguable conflict with revised Rules 26(a)(2)(B) and 26(e)(1) of the Federal Rules of Civil Procedure or with revised Rule 16 of the Federal Rules of Criminal Procedure, which require disclosure in advance of trial of the basis and reasons for an expert’s opinions.

If a serious question is raised under Rule 702 or 703 as to the admissibility of expert testimony, disclosure of the underlying facts or data on which opinions are based may, of course, be needed by the court before deciding whether, and to what extent, the person should be allowed to testify. This rule does not preclude such an inquiry.

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Key Rules (MBE/MEE)

• FRE 103 – Evidence Rulings
• FRE 104 – Preliminary Questions
• FRE 105 – Limiting How Evidence may be Used
• FRE 106 – Completeness Rule
• FRE 201 – Judicial Notice
• FRE 301 – Presumptions
• FRE 401 – Relevance
• FRE 402 – Irrelevant = Inadmissible
• FRE 403 – Excluding the Prejudicial, Confusing, etc.
• FRE 404 – Character Evidence
• FRE 405 – Proving Character
• FRE 406 – Habit, Routine
• FRE 407 – Subsequent Remedial Measures
• FRE 408 – Compromise Negotiations
• FRE 409 – Offers to Pay Expenses
• FRE 410 – Pleas, Related Statements
• FRE 411 – Liability Insurance
• FRE 412 – Victim’s Sexual Predisposition
• FRE 413, 414, 415 – Other Sex-Related Rules
• FRE 501 – Privilege in General
• FRE 502 – Attorney-Client Privilege, Work-Product Doctrine
• FRE 601 – Witness Competency
• FRE 602 – Personal Knowledge
• FRE 605 – Judge as Witness
• FRE 606 – Juror as Witness
• FRE 607 – Impeachment
• FRE 608 – Honest, Dishonest Character
• FRE 609 – Evidence of Criminal Conviction
• FRE 610 – Religious Beliefs
• FRE 611 – Mode, Order of Evidence
• FRE 612 – Recollection Refreshed
• FRE 613 – Prior Statements
• FRE 614 – Court Witness Examination
• FRE 615 – Excluding Witnesses
• FRE 701 – Non-Expert Opinion
• FRE 702 – Expert Opinion
• FRE 703 – Bases of Expert Opinion
• FRE 704 – Ultimate Issue
• FRE 705 – Disclosing Underlying Data
• FRE 801 – Hearsay Defined
• FRE 802 – Rule Against Hearsay
• FRE 803 – Strong Hearsay Exceptions
• FRE 804 – Weak Hearsay Exceptions
• FRE 805 – Double Hearsay
• FRE 806 – Impeaching Hearsay Declarants
• FRE 807 – Residual Hearsay Exception
• FRE 901 – Authentication, Identification
• FRE 902 – Self-Authenticating Evidence
• FRE 1001 – Original Defined
• FRE 1002 – Original Sometimes Required
• FRE 1003 – When Copies Generally Admissible
• FRE 1004 – Other Times Admissible
• FRE 1005 – Public Record Copies Often Admissible
• FRE 1006 – Summaries
• FRE 1007 – Acknowledged Content
• FRE 1008 – Functions of Court, Jury
• FRE 1101 – Rules’ Applicability