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Posted on June 24, 2023

How To Discredit An Expert Witness In An Illinois Divorce

Judges decide matters in an Illinois divorce. A divorce lawyer’s job is to get the divorce judge to adopt an opinion about the case that is similar to their client’s opinion of what did happen and what should happen.

The best way to get a divorce judge to adopt an opinion is to present a learned, logical opinion from an expert who is respected in their field. Parties to a divorce are allowed to elicit testimony from experts they have hired…to present an opinion that the party wants propounded.

Psychiatrists, business evaluators, scientists and other professionals may be called upon to impress an opinion into the divorce judge’s mind.

Those opinions can be about the most fundamental issues of a divorce case like who should get custody or what is a business worth.

In theory, “the trier of fact [is] not required to accept the opinion of the expert, [which] allowing [the expert witness] to testify to the ultimate issue.” Freeding-Skokie Roll-Off Service, Inc. v. Hamilton, 483 NE 2d 524 – Ill: Supreme Court 1985

Just because a judge is not “required to accept the opinion” does not mean the opinion will not impact the judge’s eventual opinion…which will impact your entire life.

A hired expert witness is referred to as a “controlled expert witness.” Controlled expert witnesses must be disclosed in advance along with their qualifications, opinions and bases for those opinions.

“A “controlled expert witness” is a person giving expert testimony who is the party, the party’s current employee, or the party’s retained expert. For each controlled expert witness, the party must identify: (i) the subject matter on which the witness will testify; (ii) the conclusions and opinions of the witness and the bases therefor; (iii) the qualifications of the witness; and (iv) any reports prepared by the witness about the case.” Ill. Sup. Ct. R. 213(f)(3)

The opposing counsel will want the judge to completely discount their opponent’s expert’s testimony. Discrediting an expert witness’s testimony can be done in one of 3 ways: 1) attacking the expert’s qualifications, 2) attacking the expert’s opinion or 3) attacking the expert’s bases for that opinion.

Attacking An Expert Witness’s Qualifications In An Illinois Divorce

Normally, a witness cannot offer an opinion while testifying in an Illinois court of law.

“[T]he general rule is that testimony of a witness’ opinion is not admissible into evidence” People v. Brown, 558 NE 2d 309 – Ill: Appellate Court, 1st Dist. 1990

Expert witnesses can offer opinions if the expert witness is “qualified as an expert by knowledge, skill, experience, training, or education”

“If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.” Ill. R. Evid. 702

This standard for being qualified as an expert is very low.

“An individual will be permitted to testify as an expert if that person’s experience and qualifications afford him or her knowledge that is not common to laypersons, and where such testimony will aid the fact finder in reaching its conclusion. The indicia of expertise is not an assigned level of academic qualifications. Rather, the test is whether the expert has knowledge and experience beyond the average citizen that would assist the jury in evaluating the evidence. The expert may gain his or her knowledge through practical experience rather than scientific study, training, or research. There is no precise requirement as to how the expert acquires skill or experience.” People v. Novak, 643 NE 2d 762 – Ill: Supreme Court 1994

Furthermore, the qualifications of an expert witness are not so much to be attacked as to point out that the qualifications have not be established. The expert witness’s counsel bears the burden of establishing their proposed witness as an expert.

“The burden of establishing the qualifications of an expert witness is on the proponent of the expert’s testimony.” People v. Novak, 643 NE 2d 762 – Ill: Supreme Court 1994

The court can find a witness to be an expert for almost any reason.

“The determination of whether a witness qualifies as an expert is within the sound discretion of the trial court.” People v. Novak, 643 NE 2d 762 – Ill: Supreme Court 1994

The standard is literally knowledge “beyond the average citizen.” The expert is going to be qualified by the judge if their attorney is remotely competent.

“A witness may thus testify as an expert if he or she has knowledge and experience beyond the average citizen that would assist the [the finder of fact[ in evaluating the evidence. There is no particular way in which that expertise had to be acquired; it could have come through formal study, training, or research, or through practical experience, in the relevant specialized field.” People v. Loggins, 130 NE 3d 432 – Ill: Appellate Court, 1st Dist., 3rd Div. 2019 (Citations Omitted)

Attacking The Expert Witness’s Opinion In An Illinois Divorce

Illinois Supreme Court Rule 213 requires that a proposed expert witness must disclose “the conclusions and opinions of the witness.” Ill. Sup. Ct. R. 213(f)(3)

The judge need not adopt the expert witness’s opinion.

The judge “is the ultimate fact finder…not the expert witness.” In re Marriage of Saheb & Khazal, 377 Ill. App. 3d 615, 628 (2007).

It is the opposing lawyer’s job to argue against the expert witness’s logic by exposing the flaws in said logic. The best way to explore the flaws in an expert witness’s testimony…is to hire your own expert witness who has arrived at conclusions and opinions more favorable to your side.

Beyond attacking the expert witness’s opinion, the opposing attorney can point out that the expert witness’s counsel must establish certain things for the expert witness’s opinion to be valid.

The party proffering the expert witness must show that “the witness’s opinion is not be based on speculation or conjecture” Volpe v. IKO Industries, Ltd., 763 NE 2d 870 – Ill: Appellate Court, 1st Dist., 4th Div. 2002

The expert’s witness’s attorney must ask the expert witness “how do you know that?” and/or “why do you have that opinion?” The expert witness’s opinion cannot be plucked from the ether.

An expert witness’s opinion must be restrained to their level expertise.

“An expert’s testimony must be to a reasonable degree of certainty within the field of his expertise to be admissible.  An expert’s statement that his or her opinions are based on a reasonable degree of certainty within a given field allows the courts to know that the opinions are an expression of the general consensus of recognized thought within the given field.” Torres v. Midwest Development Co., 889 NE 2d 654 – Ill: Appellate Court, 1st Dist., 1st Div. 2008

When the expert witness does explain how they came to their conclusion, the expert must also establish that this is how experts normally come to conclusions in this particular field.

“[T]he proponent of the evidence must convince the trial court that the information is of the type customarily relied upon by experts in the field, and that such information is sufficiently trustworthy to make such reliance reasonable.” Rios v. City of Chicago, 771 NE 2d 1030 – Ill: Appellate Court, 1st Dist., 4th Div. 2002

“Illinois law is unequivocal: the exclusive test for the admission of expert testimony is governed by the standard first expressed in Frye v. United States, 293 F. 1013(D.C.Cir.1923)The Frye standard….dictates that scientific evidence is only admissible at trial if the methodology or scientific principle upon which the opinion is based is sufficiently established to have gained general acceptance in the particular field in which it belongs.” Donaldson v. CENTRAL ILL. PUBLIC SERVICE, 767 NE 2d 314 – Ill: Supreme Court 2002

How do you prove that an expert witness did not meet this standard? You have to have another expert witness say their methodology is not generally accepted in the particular field.

The more qualified and compelling expert’s version of the methodology and the subsequent opinion will inevitably be adopted by the court.

Furthermore, even expert witnesses are not allowed to opine on some issues such as credibility and legal conclusions.

“Under Illinois law, it is generally improper to ask one witness to comment directly on the credibility of another witness.”  People v. Becker, 940 NE 2d 1131 – Ill: Supreme Court 2010

“Questions of credibility are to be resolved by the trier of fact.” People v. Kokoraleis, 547 NE 2d 202 – Ill: Supreme Court 1989

While expert witnesses can testify to the ultimate fact in an Illinois divorce case, they cannot testify as to legal conclusions.

An “expert witness [may not] testify with respect to legal conclusions.” LID ASSOCIATES v. Dolan, 756 NE 2d 866 – Ill: Appellate Court, 1st Dist., 4th Div. 2001

The distinction between an ultimate fact and a legal conclusion in family law is very blurry. Challenge any testimony that offers an inevitable legal conclusion as being an inadmissible opinion as to a legal conclusion.

Attacking The Expert Witness’s Bases For Their Opinion In An Illinois Divorce.

It is not enough to say “that expert witness is wrong.” You must say “That expert witness is wrong…and here’s why.”

An opinion is only as valid as the facts the opinion is based upon. Attacking those facts, thereby attacks the opinion itself.

Illinois Supreme Court Rule 213 requires that a proposed expert witness disclose “the bases [of the opinion]” Ill. Sup. Ct. R. 213(f)(3)

Properly researching and debunking those bases will allow a cross-examination which renders the expert witness looking foolish and their opinion inapplicable at best.

Expert witnesses do not have to testify about the bases for their opinions.

“The expert may testify in terms of opinion or inference and give reasons therefor without first testifying to the underlying facts or data, unless the court requires otherwise.”  Ill. R. Evid. 705

“The expert may in any event be required to disclose the underlying facts or data on cross-examination.” Ill. R. Evid. 705

“[O]n cross-examination, counsel may probe an expert witness’s… weaknesses in the basis of his opinions.” Wardwell v. UNION PACIFIC RAILROAD COMPANY, Ill: Appellate Court, 5th Dist. 2016

Expert witnesses must explain the facts, if asked, that they based their opinion upon. There must be some underlying set of facts the expert based their opinion upon. An expert cannot have an opinion based on other people’s opinions. An expert cannot merely explain a theory and hope the judge applies the theory to the other evidence that has been presented.

“[A]n expert witness may not parrot another expert’s opinion if that opinion represents an exercise of professional discretion or judgment.” McKinney v. Hobart Bros. Co., 127 NE 3d 176 – Ill: Appellate Court, 4th Dist. 2018

For example, a parental alienation expert cannot merely explain parental alienation and allow other evidence from the case to be applied to the theory.

The underlying facts that the opinion is based on do not need to be independently admissible in order to be discussed in open court.

“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.” Ill. R. Evid. 703

The documents and reports that make up an expert’s basis for their opinion would normally be hearsay and, thus, inadmissible. An expert can refer to those reports without the fear of a hearsay objection. “[T]he contents of the reports relied upon by [the expert] would clearly be inadmissible if offered for their truth, the [party employing the expert] seeks to allow the expert to disclose the underlying facts and conclusions not for their truth but for the limited purpose of explaining the basis for the expert witness’ opinion. For this limited purpose the statements do not constitute hearsay, and can therefore be allowed.” People v. Anderson, 495 NE 2d 485 – Ill: Supreme Court 1986

The opposing side can bring new facts to the expert witness’s attention during the cross-examination and subsequently ask the expert witness about their opinion of those facts.

“The facts or data in the particular case upon which an expert bases an opinion or inference may be those perceived by or made known to the expert at or before the hearing.” Ill. R. Evid. 703

Bringing new facts which are contradictory to the facts upon which the expert witness based their opinion upon is an excellent way to impeach an expert witness. After all, if a lowly divorce lawyer can point out an expert’s factual errors, how good is the expert really?

To impeach is to “discredit the veracity of a witness.” Black’s Law Dictionary (11th ed. 2019)

In order to impeach an expert witness, the cross-examiner may “test the expert’s opinion by asking if other facts, data, or opinions would alter his opinion. Essentially, an expert may be cross-examined with respect to reports he did not review and did not rely upon, if those reports are truly used as tools of impeachment” Jager v. Libretti, 652 NE 2d 1120 – Ill: Appellate Court, 1st Dist., 3rd Div. 1995

This allows the cross-examiner to ask the expert witness “if you had known X, would you still have recommended Y?” 

If there are prominent books or other well-respected documents that contradict an expert witness, the expert witness can be confronted with those contradictions in open court….even if the expert witness has never seen or heard of those documents. “[W]hether an expert witness could be cross-examined concerning recognized treatises in their field where they did not purport to base their opinions on the views of these authorities. [S]uch cross-examination [is] permissible, despite the hearsay nature of the treatises, in order to insure that expert testimony will be more accurate and a more effective tool in the attainment of justice.“ Walski v. Tiesenga, 381 NE 2d 279 – Ill: Supreme Court 1978

For example, somewhere within the 1248 pages of Shannon Pratt’s Valuing A Business: 6th Edition: The Analysis and Appraisal of Closely Held Companies will be a line that directly contradicts whatever a business valuator has just testified to. You are allowed to read that line to the expert evaluator and ask them why the industry standard book directly contradicts their testimony (this is always fun).

Almost any document that can be testified to as being “a very good book, a standard book [or] a good source [can be used to impeach an expert witness].” Bowman v. University of Chicago Hospitals, 852 NE 2d 383 – Ill: Appellate Court, 1st Dist., 1st Div. 2006 (quotations omitted)

Ask the expert if they’ve heard of the book you wish to impeach them with. The expert will either look like a fool by not being aware of the authority of the book or the expert will look like a fool when the book contradicts their opinion.

There is a unique pleasure in proving some know-it-all expert does not really know what they are talking about.

While conducting a deposition, I once asked an accountant, “You are not very good at math are you?”

To which the accountant huffed, “Yes. I am!”

My further inquiry was, “Okay. But, considering the errors we just discussed…are you good at math for being an accountant?”

The accountant nervously laughed to relieve the tension in the room and said, “Ha. Maybe not.”

If you would like to talk about the expert witness your spouse hired and how to discredit them before a hearing, contact my Chicago, Illinois family law firm to schedule a free consultation with an experienced Illinois divorce attorney.

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Russell Knight

Russell D. Knight has been practicing family law as a Chicago divorce lawyer since 2006. Russell D. Knight amicably resolves tough cases while remaining a strong advocate for his client’s interests.

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