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How To Effectively Cross Examine An Expert Witness

On Behalf of | Jan 10, 2023 | Firm News

An Excellent Reputation
Built On Success In The Courtroom

By William B. Smith
Abramson Smith Waldsmith
San Francisco, California
415-421-7995 /

January 20, 2006

I. The four biggest mistakes:

A. No plan. On the fly/Too ambitious/Don’t know when to stop.

B. No control. Leading questions/Object as non-responsive/Don’t take bait i.e. explain/draw.

C. No patience. Not satisfied with making points; need to argue with expert/Saving it.

D. No preparation. This starts at deposition stage right up to trial. Scripted but open ears.

II. General rules of cross examination:

A. Irving Younger (Cornell):

1. Three qualities: Experience/Talent/Preparation.

2. The ten commandments:

-Be brief. Generation X and Y jurors are not patient.

-Short questions, plain words.

-Ask only leading questions. Exercise control.

-Never ask a question to which you do not already know the answer. You are looking for evidence to support your final argument.

-Listen to the answer.

-Do not quarrel with the witness.

-Do not permit the witness to explain.

-Do not ask the witness to repeat the testimony he gave on direct.

-Avoid one question too many.

-Save the explanation for summation.

3. The 11th commandment: Be visual: video depositions/use screen/use board.

B. Francis Wellman: The Art of Cross-Examination, 1903. Less is better: read excerpt.

III. Preparation!!

A. Deposition preparation: Ten things you MUST do before trial:

1-The deposition notice duces tecum: request the ENTIRE file and CV.

2-Review the expert declaration.

3-Consult with your expert. Send CV: Qualified? Suspicious? Gather writings.

4-Pin down the expert at the deposition: Video deposition.

-The file: MARKING and EXAMINING it, including the CV .

-The opinions: the ALL opinion question to set up motion in limine i.e. anti-sandbagging motion

-The bases for each opinion. : ltd basis = ltd opinion.

-Often lazy. Dig for ALL bases.
-Hearsay is OK. Read 801b. But…must be “of a type that reasonably may be relied on by an expert in forming an opinion”. Trustworthy + necessary. Must explore this at deposition.

5-Work to be done in future: Usually reading opponent expert’s depositions. Some experts use this as an “out”so cannot be pinned down at deposition.

-The “out” is an effort by an expert to add to or change his own opinions at trial in the guise of reacting to the opponent’s experts. How prevent? Establish that additional opinions will be a critique of what opposing expert does and NOT new original opinions by the expert. Shut the door.

-Never agree to re-depose opposing expert. Why not? Let him off hook + expense.

6-Bias set up:

-How involved? Interest/bias. Axe to grind?

-Work predominately for one side? Frequency with this attorney?

-Amount of money charged?

-Percentage of income from testifying? The professional witness/whore.

-WHEN reached opinions? Before had information upon which to base it?

7-Deferral/disqualification questions? Example: Medical witnesses: different specialties/different experience e.g. with a fracture type/familiarity with patient e.g. patient’s symptoms.

8-Other prior testimony?

-Expert’s records? Depositions? Trial transcripts? Billing?

-FRCP, Rule 26a2B: Expert report required that lists any other cases in which the witness has testified as an expert at trial or by deposition within the preceding 4 yrs.

-How obtain? Either request in duces tecum deposition notice or get from court.

9-Dig for favorable concessions. Reaching the common ground.

-Doctor: need for future surgery/causation/life expectancy/need for attendant care etc.

-Economist: discount rate/work life expectancy.

-CPA: method of evaluation of the destruction of a business.

10-Look at CACI and refresh memory on how a jury is to evaluate the believability of expert testimony and how a jury is to “weigh” it. . READ…

-CACI 219: Consider expert’s training, experience, facts relied on and reasons for opinion.

-CACI 221: When weighing conflicting expert opinions examine qualifications, facts or other matters relied on and reasons given for each opinion.

B. Digesting the deposition.

-Summarize it. Try DepoExpress.com: $1.50/page, 5 day turnaround, a cost.

-Outline the opinions and bases (like diagramming a sentence)

-Give deposition to your expert to review and critique. Orally.

C. Digesting the witness.

-Former testimony: Gather it….if do not already have.

-Verdict publications like Verdict Search California (formerly Jury Verdicts Weekly).

-Deposition banks. (e.g. SFTLA).

-Other lawyers who do what you do. I got program material a vocational rehabilitation expert in swimming pool case re “How to be an Expert Witness”.


-His/her website. Amazing representations!!

-Web in general.

D. Digesting the file.

-Complete? Anything missing? Ask yourself why “x” included? Source? .

-Independent research?

-Articles/books of deponent? Set up for Evidence Code, section 721 impeachment.

-Check out qualifications: Licensed? Certified? Degrees? Writings? Organizations? Discipline? Discharged?

IV. Preparing the PLAN of attack. Purpose: Diminish the WEIGHT of the expert. Visualize the “weighing” process to be argued in final argument. . Guideline: Evidence Code, section 721a. READ it….

A. ID the favorable concessions. Adds weight to your side of the scale.

B. Where is expert weak and vulnerable to attack? Subtracts weight from opposing expert’s side of the scale.

1. Direct attack on opinion:

-Undercutting opinion: Inadequate training + experience in area. .

-Jack of all trades.

-Ivory tower. Professor/government employee.

-First such case. Don’t confuse with first time as an expert witness.

-Eliminating opinion: This can be done by motion in limine, a trial voir dire of the expert , or directly during cross examination.

-Deferral/disqualification question.

-Cannot meet the legal standard. Does not know standard or only “possible”/Is the subject matter beyond common experience?

-Expert may not testify on legal issues. Although an expert may be allowed to testify on ultimate issues to be decided by the jury, an expert cannot offer opinions on subjects like nondelegable duty, negligence etc. .

-Improper basis for opinion. .

-Remember: Evidence Code, section 801b says hearsay OK but must be trustworthy + necessary.

-Two cases:

-Korsak v. Atlas, (1992) 2 CA4t 1516: The falling shower head case with ME expert who does an informal hotel maintenance survey. Not reliable or necessary. I have in a current case. This comes up.

-Whitfield v. Roth, (1974) 10 Cal 3d 874: Two defense doctors allowed to testify about whether early x-rays showed a brain tumor. Expert #1: radiologist called in 4 colleagues who agreed with him it did not. Expert #2: neurosurgeon at Stanford showed x-rays at grand rounds to 50 students, residents and faculty and all agreed with him it did not. Cannot rely on the out of court opinions of others as a basis. Neither trustworthy or necessary.

-Reducing the number of experts. .

-Changing opinion. Facts did not consider because overlooked or ruled them out. The erroneous factual basis. Opinion only as good as its foundation. Assume additional facts and see if expert will change opinion. .

-Example: Appraiser’s opinion re real estate value based in part of comparables. Point out the comps are wrong, incompatible or were overlooked. Might this change your opinion? Then change basis and test it.

-Correcting opinion. Point out computation errors or clear mistakes.

-Example: CPA’s, economists, engineers, architects etc.

-Narrowing scope of opinion.

-Example: Defendant expert: Product not defective. Plaintiff cross exam: Product not defective in design? Not saying no manufacturing defect possible?

2. Indirect attack on opinion: Credibility x 3.

-The reasons for the expert’s opinion. (Evidence Code, section 721a)

-Bias: interest, money, frequency testifies for one client, type of client or atty, 1 sided, % of income (professional witness).


-Former testimony under oath.

-Other publications: Evidence code, section 721b. READ it…. Reliance NOT necessary. If foundation satisfied, may read in portions of writings but may not receive as exhibit in evidence. .

-Incomplete or inadequate work up. E.g. one visit to defense doctor v. many to treating physician.

C. List all the points in order of strength. Pick out the 3-4 best points and plan to establish them clearly and stop.

D. Create the outline of a cross examination with all references: The PLAN.

-Points: page and line. Don’t write out questions verbatim except impeachment opportunities.

-Have impeachment ready. Video depositions /Scan entire deposition so can do on the “fly” or plan ahead.

-Electronic trial: have a print out of all exhibits with bar code ready and make sure you have copies for opponent.

V. Executing the PLAN at trial.

A. Prepare motions in limine:

-Anti sandbagging.

-Demonstrative evidence: animations you expect.

-Knocking out expert opinion altogether.

B. Each expert: your QUIVER.

-Deposition + summary.

-Original deposition filed with court.

-Entire deposition scanned if using electronic trial.

-Your outline with all references + list of exhibits.

C. Consider voir during the expert to head off the opinions at the pass. . Strategy: Knock it out before jury hears it versus handling it on cross.

D. Be flexible. Ask yourself: Did he hurt me? If not, STOP. Remember Wellman quote.

E. Illustrating the points: Visualize. Put on paper and mark it. Jurors will write it down.

-Example: Recent MM case, def trained in Philly, mentor in Philly, expert from Philly with strong connection with mentor. But expert denied that knew def and mentor had nothing to do with his involvement. I wrote Philadelphia on sheet before any questions.

-Visually attacking opposing expert BEFORE he/she testifies: Plaintiffs: consider discrediting defense expert with your expert who goes first. Question your expert: Read opposing expert deposition? Outlined opinions?
Show me list? Challenge opinions and qualifications.
Advantages: allows jury to do early comparison of experts and the issues.
Disadvantage: telegraphs your cross examination of opponent’s experts.

F. Examine expert’s file taken to stand. Mark it so cannot take it with him in evening.

-Example: The expert who forgot to remove a sticky saying: “Meet with my lawyer to go over my testimony”

G. Impeachment: 3 steps…no requirement to show it to him or explain.


-Video impeachment: Explain how it works. Same steps + “I’d like to play page x, lines 1-10 of Mr. Y’s deposition”. Witness impeaches himself.

H. Attack animations/experiments. Motions in limine: no foundation.

-Lots of preparation with your animator. Very technical.

-Look for inaccurate/untrue assumptions.