November 15, 2012

Consider a Blind Expert Witness

By Dr. Ken Broda-Bahm: 


Justice may be blind, but hired experts can see pretty darned
well in our litigation system. No, a responsible expert won’t lie
in order to support their client. But yes, a knowledge of who the
client is can’t help but have at least a subtle influence on the
resulting testimony. But that is our adversarial system, right?
Both sides hire the best they can find who are willing to support
their theories, and the two sides fight it out, aided by
cross-examination and a skeptical and attentive jury. That is the
idea, but in practice, there are a few problems with that model.
For one, the adversarial model can end up elevating the value of
the less common expert opinion to the point that a view that,
maybe, only one in a hundred experts would sign on to becomes one
of only two expert opinions presented in court. For another, the
jurors themselves may be desensitized by the knowledge that all
parties are paying for their opinions and simply decide to set
aside the “hired guns” and figure things out on their own. Yet a
third problem is the effect that this model has on the experts
themselves: Academics who are used to following the facts
wherever they lead, without prejudgment or bias, are
uncomfortably thrust into an adversary system and find themselves
working not wholly for the truth, but in order to advance their
client’s case.

Of course, all that shouldn’t be taken as a statement that
experts as a class are dishonest. That isn’t what I’m saying.
I’ve worked with many experts, and to a person they’ve been
honorable and careful women and men who understand that they
cannot mislead the jury and cannot risk being seen as just
another lawyer. But they also cannot take their eye off the
ultimate purpose of their testimony and the reason they were
hired. It is fair to wonder if there’s another way. According to
one model, proposed in a 2010 article in the New York
University Law Review
(Robertson, 2010) and recently tested in an
experiment published in a forthcoming edition of the Journal
of Empirical Legal Studies
(Robertson & Yokum, 2012), there is a
simple solution that would improve both the accuracy and the
credibility of expert testimony: blind experts. No, I don’t mean
hiring Stevie Wonder as your expert witness, I mean
employing a system that keeps the expert blind to the identity of
the client until the initial report is completed. The idea has
implications for how you might think about your experts now and
in the future, so this post will explore that idea. 

The Idea: Blind is Better

Christopher T. Robertson, a law professor at Harvard University
and the University of Arizona, proposed the idea two years ago in
an article simply entitled “Blind Expertise” (Robertson, 2010). The piece provides a
comprehensive examination (for cheaters, a Readers’ Digest
condensed version is available here) of the benefits and the implementation of
a system that would allow parties to employ experts who are
initially blind to the party they’re working for. The following
is what Robertson proposes:  

  • If they wish, parties would contact an intermediary
    organization. Members of that organization, also blind to the
    identity of the party, would then select from a pool of
    prequalified experts based on criteria provided by the
  • The hired expert would learn about the case via a screened
    set of materials and, without knowing the identity of the hiring
    party, would draft the preliminary expert report laying out the
    main conclusions. 
  • If the conclusions are not helpful to the
    hiring party, that party would simply pay and walk away. The fact
    that a blind expert was consulted would not be subject
    to discovery. 
  • If the conclusions are helpful, on the other
    hand, the blindfold would be lifted and the expert would be able
    to testify not only about their conclusions, but also about the
    process and the fact that their initial report was produced under
    blind conditions.  
  • In the event that a party chooses to use a blind witness,
    that party would need to disclose all prior blind witness
    arrangements (to prevent the party from trying multiple times
    until they get a ‘hit’ with a blind expert). 
  • Nothing would prevent either party from hiring a paid expert
    instead of or in addition to the blind expert. 

The benefits of using initially blind experts in this manner,
according to Robertson, is that their opinions are more likely to
be consistent with the scientific mainstream, more comfortable
for the experts themselves, and more likely to be viewed as
credible by jurors.   

The Study: Blind is More Credible

To test the result of blind experts on jurors’ views of expert
testimony, Robertson and University of Arizona Colleague David
Yokum (Robertson & Yokum, 2012) conducted
an experiment using 275 mock jurors. The national sample reviewed
video recordings of a 35-minute staged medical malpractice case
with experts on each side testifying on the question of liability
in a failure to diagnose a case. Participants were randomly
assigned to conditions in which either the plaintiff or the
defense expert (or neither, in the control condition) was
identified as a blind expert, and the researchers also varied
whether jurors did or did not receive a special instruction from
the judge telling jurors that they “may,” based on the method,
consider a blind expert to be more credible. 

The researchers found that, even without that special
instruction, the blind expert was significantly more credible and
significantly more persuasive. When all other aspects and facts
in the case and the content of the opinions were kept the same,
the use of a blind expert doubled the odds of a favorable verdict
and significantly increased damage awards for the plaintiff, or
decreased damage awards for the defense, by over $100,000 dollars
in each case. 

And remember, that is when there is no change to the content of
the testimony, other than the description of the blind procedure.
It is also quite conceivable that a blind witness would perform
better because they would be more confident, would feel more
unbiased, and could come across as more of a teacher and a “third
voice” in the litigation. These traits could heighten blind
expert’s persuasiveness even more. 

So What Are the Implications? 

One, Consider a Blind Expert. 

As Robertson highlights in the 2010 article, there are some
reforms that should be undertaken before the practice of using
blind experts becomes widespread. For example, reforms should
ensure unsuccessful reviews don’t become part of discovery, and
also discourage litigants from adopting a “try, try, again”
strategy in the event that an initial blind review isn’t in their
favor. However, with guarantees like that, or maybe even without,
it is easy to imagine some cases that would benefit greatly from
a blind approach. For example, think about a medical malpractice
case in which the defense is very confident that nine out of ten
experts, maybe even ninety-nine out of one hundred experts, would
find no breach of the standard of care. Under the current system,
the plaintiff could still find that atypical expert and, to the
jury’s eyes, the “one-in-a-hundred” becomes “one-in-two” in the
courtroom. If, however, the defense expert was selected blind,
and the plaintiff’s expert was a hired gun, it is more likely
that jurors would see an obvious difference and a wide
credibility gap.

Of course, it is also clear that there are cases where it
wouldn’t be wise to use a blind expert. If your side of the case
requires testimony that cuts against the consensus of likely
opinion, then it would still make sense to use a hired expert.
There could also be cases where it would make sense to use hired
testimony to supplement a blind expert (perhaps requiring
modifications to cumulative testimony rules), because the hired
expert is more qualified or a better teacher.  

There are clearly some elements that need to be worked out, but
it is an intriguing idea. And medical malpractice defense
seems like an ideal setting for trying it out. 

Two, Play Up the “Blind” Features in Your Conventional

Even if you don’t move to a blind expert model right away, the
idea and the research provide a good reminder to emphasize those
aspects of conventional expert testimony that are likely to
strike jurors as less biased and more credible. The following are
messages that add credibility to hired witness testimony. 

I said the same thing, or consistent things, before I was
hired, in previous publications and presentations.  

I could have gone even further (on damages, liability,
etc.), but I didn’t.

Their expert uses the same methods, makes the same
assumptions, or reaches the same conclusion. 

In short, it makes sense to take a close look at your expert
witness testimony and emphasize those areas that, from a juror’s
point of view, highlight the quality and the independence of the

While the research reviewed in this post may point to a way to
offer more effective expert testimony in at least some contexts,
for the present we are likely stuck with experts who are
themselves stuck in an adversary system. In most cases, those
experts will be perceived as hired guns. But as one earlier study
(Cooper & Neuhaus, 2000) demonstrated,
that perception is likely to be most damaging when testimony is
unclear or communicated poorly. So, for now at least, it is best
to hire a hired gun who teaches effectively.


Other Posts on Expert Witnesses: 

Robertson, C. T. (2010). Blind Expertise New York University Law Review, 85,


Robertson, C.T., & Yokum, D.V. (2012). The Effect of Blinded
Experts on Jury Verdicts Journal of Empirical Legal Studies,
(4), 765-794

Photo Credit: Ken

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