Attacking the experts

Expert Credibility Under Attack: When Past Misconduct Becomes Fair Game

Expert witnesses play a crucial role in personal injury litigation, often providing the technical foundation that can make or break a case. However, as this First Department decision demonstrates, an expert’s credibility can become vulnerable when their past professional conduct comes under scrutiny. The case illustrates an important principle: when experts claim specific qualifications as the basis for their testimony, opposing counsel may be permitted to explore relevant aspects of their professional history — even incidents that occurred decades earlier.

This ruling has particular significance for cases involving biomechanical evidence and other technical expert testimony, where the foundation of an expert’s qualifications directly impacts the weight their opinions carry with a jury.

Jason Tenenbaum’s Analysis:

Montas v Abouel-Ela, 2017 NY Slip Op 07413 (1st Dept. 2017)

“Plaintiff has not demonstrated conduct by defendant’s counsel that would warrant reversal. Defendant’s counsel was properly permitted to cross-examine plaintiff’s expert rebuttal witness about the circumstances surrounding his suspension from chiropractic school for falsely reporting that he had seen patients, a matter relevant to his credibility (see generally Badr v Hogan, 75 NY2d 629, 634 ; Spanier v New York City Tr. Auth., 222 AD2d 219, 220 ). Although the conduct was 30 years ago, the witness opened the door to its relevancy by claiming that his expert knowledge of biomechanics came, in part, from his training as a chiropractor.”

Unfortunately, this case suggests that we look at the quality of the defense experts who testify. In their former lives, many a defense expert well..somethings are better left unsaid.

Key Takeaway

The court’s decision reinforces that expert witnesses cannot selectively highlight their qualifications while shielding related aspects of their professional history from examination. When an expert claims specific training or education as the foundation for their expertise, they effectively open the door to cross-examination about relevant incidents from that same background — regardless of how long ago they occurred. This principle applies equally to expert testimony foundations across various medical and technical disciplines.

Legal Significance

The First Department’s decision in Montas v Abouel-Ela establishes important boundaries for expert witness cross-examination in New York personal injury litigation. The court’s analysis rests on the “opening the door” doctrine—a principle that parties who affirmatively introduce evidence on a particular subject cannot complain when the opposing party explores related matters that might otherwise be inadmissible or prejudicial.

Here, the plaintiff’s expert specifically testified that his biomechanical expertise stemmed in part from his training as a chiropractor. By invoking this educational background as a source of credibility, the expert invited inquiry into whether that background actually supported the claimed expertise. The defendant discovered that during the expert’s chiropractic training, he had been suspended for falsifying patient treatment records—conduct that directly contradicted claims of professional integrity and reliable clinical training.

The court’s ruling that this 30-year-old misconduct remained relevant reflects several considerations. First, the misconduct involved dishonesty—falsifying records—which bears directly on the witness’s credibility regardless of how much time has passed. Courts consistently hold that evidence of prior dishonesty remains relevant to credibility assessments. Second, the misconduct occurred during the very training period the expert invoked as supporting his qualifications. This temporal and substantive connection made the suspension highly relevant to whether the claimed training actually provided reliable foundations for the expert’s opinions.

The decision cites Badr v Hogan, 75 NY2d 629, 634 (1992), which establishes that evidence bearing on a witness’s credibility generally merits admission even when it might be prejudicial. Expert witnesses, despite their specialized status, remain subject to the same credibility rules as fact witnesses. When experts invoke their backgrounds to establish expertise, they cannot shield those backgrounds from scrutiny.

Practical Implications

For attorneys retaining expert witnesses, Montas underscores the critical importance of thorough vetting before designating experts for trial testimony. Background investigations should extend beyond reviewing an expert’s credentials and publications to include disciplinary history, professional licensing issues, and prior misconduct that might surface during cross-examination. When experts have checkered histories, attorneys face difficult strategic decisions about whether potential impeachment risks outweigh the value of the expert’s opinions.

The decision also highlights the strategic risks experts face when explaining the bases for their opinions. The plaintiff’s expert could have relied solely on his biomechanical engineering credentials without invoking his chiropractic training. By choosing to cite that training as supporting his expertise, he opened himself to devastating cross-examination about misconduct during that very training period. Experts and their retaining attorneys must carefully consider whether invoking particular credentials creates more vulnerability than benefit.

For defendants and their counsel, Montas provides a template for effective expert impeachment. When experts invoke specific backgrounds or training as supporting their qualifications, defense counsel should investigate whether those backgrounds include disciplinary issues, academic problems, or professional misconduct. Even decades-old incidents may remain admissible if they occurred during periods the expert claims as foundational to current expertise.

The decision also has asymmetric implications. Jason’s comment—“we look at the quality of the defense experts who testify. In their former lives, many a defense expert well..somethings are better left unsaid”—acknowledges that defense experts face the same vulnerabilities. Insurance company medical examiners and defense experts often have complex professional histories that may include disciplinary actions, malpractice claims, or academic issues. Plaintiffs’ counsel should apply the Montas principle equally, investigating defense experts’ backgrounds for impeachment material.

The practical lesson extends beyond expert witness practice to broader litigation strategy. The “opening the door” doctrine operates throughout trials, not just in expert testimony. Parties who affirmatively highlight particular aspects of their case invite opposing counsel to explore related matters in ways that might otherwise be prohibited. Strategic decisions about what evidence to present must account for what responsive evidence those presentations may permit the opponent to introduce.

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