Cross-Examination of Expert Witnesses – Mock Trial Strategies

Introduction & Session Logistics

  • Session shortened to 04:25 PM–04:30 PM so instructor can meet career-planning students.
  • Continuation from previous class: direct examination of expert already completed; focus now shifts to cross-examining the expert witness.

Role of Expert Cross-Examination

  • Goal: undermine or limit weight of expert testimony rather than merely repeating direct.
  • Unique scenario discussed: an “inside-man probability” expert—illustrates how broad (and sometimes dubious) expertise can be admitted in mock-trial fact patterns.

Exposing Bias & Financial Incentives

  • Classic first question: “Doctor, how much are you being paid to sit here today?”
    • Expert in case study paid 30,00030{,}000 by the defense.
    • Follow-up points:
    • Highlight payment source (defense) to suggest opinion is purchased.
    • Create “hired-gun” image—especially potent if expert always testifies for one side.
    • If expert testifies for both sides, bias argument weaker but still usable.

Challenging Credentials & Experience

  • Establish if expert has never been qualified by a court before:
    “This is your first time testifying in court, isn’t it?”—implies lack of real-world validation.
  • Apply especially to non-traditional experts (e.g., DMV statistician) who may lack formal courtroom recognition.

Questioning Methodology & Missing Tests

  • Mock-trial police work is often intentionally sloppy:
    • No fingerprints, DNA, or basic forensic work.
    • Highlight each omitted test to show conclusions rest on incomplete investigation.
  • Example for tomorrow’s closing: prosecution skipped calling the police officer; defense capitalized by asking “Where’s the officer? Where are the prints?”

Attacking Foundations & Data Reliability

  • Key concept: “Garbage In, Garbage Out (GIGO)”.
    • Personal-injury economist example: Based 2,000,0002{,}000{,}000 lost-earning projection entirely on plaintiff’s oral statements—no bank statements or tax returns reviewed.
    • Counsel wrote G I G O on board; forced expert to define acronym; ended cross with “No further questions.”
  • Techniques:
    • List every document the expert didn’t review.
    • Ask whether opinion would change if underlying info is inaccurate.

Exploring Alternative Explanations

  • Hockey fatality case recap:
    • Expert said blunt-force impact was “most likely” cause of death but report also noted ruptured aneurysm.
    • Cross formula:
    1. Re-affirm expert’s main opinion.
    2. Establish existence of aneurysm.
    3. Lock expert into admitting they “cannot rule out” aneurysm as cause.
  • Lesson: Present jury with an equally plausible narrative to create reasonable doubt or reduced damages.

Using Authoritative Sources for Impeachment

  • If expert touts treatise as 100 % authoritative, locate contrasting passage:
    • Read excerpt aloud.
    • Confirm expert’s prior statement of total agreement.
    • Ask, “Did I read that correctly?”—creates direct conflict between expert and their own source.

Witness-Control Techniques

  • Closed, leading questions; aim for one-word answer.
  • Phrases toolbox:
    • “Directing you back to my question, yes or no …”
    • “Nevertheless …” when witness dodges.
    • “May I take that as a yes?”
    • “Thank you for that answer, Mr. Smith; my question was …”
  • All designed to keep testimony within examiner’s narrative timeline.

Non-Responsive Answers: Objections & Motions to Strike

  • California practice (instructor’s strong preference):
    • “Objection, Your Honor, move to strike everything after the word ‘yes’ as non-responsive.”
    • Repeat on successive violations; on third attempt also request judicial admonition of witness.
  • Advantages of combining objection + strike:
    • Avoids forgetting to strike.
    • Efficient within strict time limits.
  • Jurisdictional contrasts:
    • Midwest/Iowa mock-trial tradition expects counsel—not judge—to control witness, so strikes are rarer.
    • Some states (e.g., Colorado) teach immediate interruption: “Non-responsive!” mid-sentence.
    • Always test judge early: first cross should include a strike request to read the bench’s attitude.
  • Narrative objection: “Objection, witness is lapsing into a narrative.”
  • Specificity requirement: Only the inadmissible portion is stricken; counsel must identify precise segment.

Time Management & Ethical Framing

  • Remind court subtly: “As Your Honor is aware, proceedings in this jurisdiction are strictly timed.”
    • Never break immersion by mentioning “mock trial.”
  • Warning about witness stalling: note that verbose answers run the clock; supports motion to strike.

Professionalism & Courtroom Etiquette

  • Avoid overt rudeness; let witness finish when possible before striking—unless judge allows mid-answer interruption.
  • Refer to opposing counsel, expert, and judge with formal titles.
  • Consult team norms & coach instructions; strategies differ by circuit.

Practical Mock-Trial Tips

  • Have co-counsel ready to remind speaker to move to strike if they forget.
  • Objection arguments do not count against time—use them strategically to slow opponent or collect thoughts.
  • Mix of tactics impresses evaluators: attempt polite control first, escalate to formal strike when necessary.

Connections to Previous Lectures & Materials

  • Builds on prior session’s direct examination concepts.
  • Reinforces earlier discussion of alternative causation (aneurysm) and treatise impeachment.
  • Upcoming content: full closing argument video will illustrate how missing forensic evidence is exploited.

Real-World Relevance & Implications

  • Fee bias and lack of foundation are real trial issues, not just academic.
  • Practitioners must tailor cross for jurisdictional norms—e.g., West Coast judges more willing to strike.
  • Ethical dimension: Counsel must balance zealous advocacy with respect for witnesses and court.