Can a Biomechanical Expert Offer Specific Causation Testimony

A prior post discussed how, at least in Nevada, courts will not allow specific causation testimony from biomechanical experts.  But what if the expert has medical training?

Let the Expert Pick a Box

Plaintiff disclosed a retained expert in accident reconstruction and biomechanics, who had a Doctorate of Chiropractic and a Ph.D. in epidemiology.  At deposition, I needed to clarify whether he was offering medical opinions or biomechanic opinions.  He testified that he would not offer any medical opinions regarding Plaintiff’s alleged injuries:

16 Q. That helps me immensely. I think — would it
17 be fair to say that you are testifying in this case as a
18 biomechanical expert with medical knowledge, training,
19 and experience, as opposed to a medical expert in your
20 capacity as a chiropractor?
21 A. Yeah, I’m not — I’m not testifying
22 specifically as a medical expert or a chiropractor.

I wanted that testimony because it meant if the expert was solely offering biomechanical opinions, then he could not offer the specific causation opinions in his report.  His proposed testimony was that the forces Plaintiff experienced could have caused Plaintiff’s injuries:

7 Q. I’m moving on to the bottom of page 18 and on
8 to page 19. As to the injuries that you discussed such
9 as traumatic brain injury, cervical spine injury, you’re
10 offering a specific opinion that [Plaintiff] suffered that
11 particular injury and that this particular injury is
12 consistent with the biomechanical forces she would have
13 experienced in this particular collision. Did I get
14 that right?
15 A. Well, I’m not personally making a diagnosis.
16 I’m just taking that from the medical record. But the
17 second part of your — the second part of your question
18 is correct.
19 Q. I’ll rephrase it, make sure I get it right.
20 So you are taking the diagnosis from the
21 physicians in this case and then evaluating whether that
22 specific injury that they diagnosed is consistent with
23 the biomechanical forces that you calculated. Did I get
24 it right this time?
25 A. That’s — you did get it right.

As far as I was concerned, that was the exact type of opinion that Nevada presently bars. 

He didn’t do anything in his box.

With the expert now squarely in the biomechanical box, I set about attacking that opinion too.  If the accepted role of biomechanical testimony in Nevada is to compare forces, this expert conducted calculations about various forces that may have occurred in this accident, but he did not compare them to anything.

8 Q. I’m on page 17 of your report now and I’m
9 looking at your graph. I want to make sure I’m matching
10 the graph lines to the chart correctly. And let’s see,
11 so Head X, is that the peak at 31.5 G?
12 A. Yes.
13 Q. Head Z is 11.5?
14 A. Yes.
15 Q. Lumbar X peaks at 23.4?
16 A. Correct.
17 Q. And Lumbar Z peaks at 6.8?
18 A. Correct.
19 Q. In your report, do you compare these G forces
20 to any experiences that a jury might have in normal,
21 everyday life?
22 A. There wouldn’t be any
23 [PLAINTIFF’S COUNSEL]: And I’m just going to lodge an
24 objection to form.
25 ///
2 Q. I’m sorry, Dr. [Expert], I didn’t hear your
3 answer.
4 A. There wouldn’t be any comparison of this level
5 of acceleration to everyday life unless you were
6 possibly a rodeo clown or an NFL player.

In summary, the expert had an opinion about the forces that could have been generated, but did not compare or contrast the alleged accident forces with the forces that a juror may experience in daily activities.  His impromptu comment at deposition about the forces was not contained in his report, nor did he provide the facts or calculations he used to compare the forces generated in this event to any other event. 

What happened?

It’s a long story, but the case went away without this issue getting further than motions.