Engineers New to being Expert Witness -- Scientific Method

DISCLAIMER: I am not a lawyer and anything written here is strictly my opinion and should not be taken as legal advice.

Once upon a time, the Courts in the U.S. would accept testimony from anyone who claimed to be an expert. So, courts would listen to the carefully worked out horoscope from an astrologist as well as the results of a exacting chemical experiment. There was no real distinction made.

Then came Frye v. United States in 1923, Court of Appeals in the District of Columbia. Here was a case where the use of blood pressure as a means of lie detection was submitted as evidence. The judge threw the evidence obtained this way out of the court as it was not an accepted criteria amongst the experts in the field. This case created the test for expert testimony: is it generally accepted in the scientific community for which it applies. This eliminated the lunatic fringe from testifying in court. Hurrah! Some rigor must be used in collecting evidence, evaluating and testing it. The principles the conclusions are drawn on must be generally recognized as valid in the field.

Thus it has become important to courts to get their evidence based on the Scientific Method. There are various forms to the Scientific Method depending on who you ask or how it is defined, but basically it is
a. Recognizing a problem or question exists.
b. Collecting information, data, and observations about it.
c. Analyzing the information
d. Make a hypothesis which explains known data and observations
e. Test the hypothesis. (If it fails then go back to 'b' with your results)
f. Make a final hypothesis which explains all known or observed phenomena
and test results.

When you are preparing for a case, that is the touchstone they will be using to determine your qualifications and your findings--can you cast your information in to a form which shows you followed this method, are your data acquired through scientifically rigorous means and are your conclusions based on accepted rinciples.

There are other criteria involved in being an expert witness, of course, but this is one of the key points to be aware of in preparing.

I will be writing more on other case law and the application to being an expert witness.

Messing up the Profession of Expert Witness:

Yesterday I helped with a fire scene in Beverly Hills. What a mess! The fire investigator was looking at the burn and char and saying it started below the floor, the fire department was calling spontaneous combustion of used paint rags, and the adjustor for the property was going along.

I got called in as a Forensic Engineer because there was a mass of electrical wiring at the point of origin. Very suspicious!

However, although it seemed likely I could not find a single wire that showed shorting or arcking evidence. Even though breakers had tripped there was none anywhere at all. This implied the breakers tripped fast enough during the fire to completely protect the wiring and house. Good, but what happened?

We got our hands on the original fire department Fire Investigator and found pictures of the sheet rock before over-haul. Ah=-hah! Inverted-V pattern! Different scene entirely. We called the Fire Department investigator and he was very glad to get it pointed out and was going to re-review the scene. We also called the property Fire Investigator and he wasn't interested! Amazing! He could be given a key indicator as to fire origin, but since he had already written his report he was just going to leave it at that.

This certainly makes a poor representation for the profession. This doesn't just make him look bad, but it gives the whole profession of Fire Investigators a taint of incompetence. Solution: as a start, when you run into incompetent work, point out that their professional work needs to be brought up to a professional level. Maybe just pointing it out will get them to at least think about it.


Derek Geer
Forensic Engineer
San Diego, California
www.geers.com

Natural Law versus the NFPA

I prefer being on the side of the Natural Law when it comes to being an expert witness.

Obviously the National Electrical Code was written to make electricity safer in our homes and businesses--fire or electrocution being the major dangers of electricity. In checking with other expert witnesses in depositions and cross-examinations I noticed the NEC is treated, or at least talked about, as natural laws of nature rather than man-made standards which have changed over the years and will undoubtedly change in the future.

The key difference is the semantics used: "The fire started because of a violation of NEC Code". This is never true; court rooms to the contrary. A fire always starts due ignition temperatures, fuel and an oxidizing agent. It continues according to the laws of physics, thermodynamics. That's all. The paper and gasoline and wood and air were never taught the NEC or NFPA 921. An Expert Witness may intuitively know this, but be dealing with a court system does not.

I am sure most expert witnesses don't need this advice, but I have been surprised by the people I have run into that weren't clear on this.

Derek Geer
Forensic Engineer
San Diego, California
www.geers.com

The Causal Chain -- mistakes in reasoning

Causal: "Of, involving, or constituting a cause" (please don't read it as "casual" which means "relaxed or informal")

I ran into a forensic engineer/expert witness from the West Coast who is famous (infamous) for his time consuming work. He proudly promotes himself as the most thorough forensic engineer around. He will spend days and days analyzing a stove which was the proximate cause for a fire. Something that most forensic engineers would take less than a day to complete.

What is missing is inteligence. Quantity mistaken for quality.

Any proximate cause is tied to a causal chain--a series of cause-and-effect leading from proximate cause to loss, damage or injury.

What is this 'expert witness' doing? He is examining everything whether it could be on the causal chain or not. Somewhat like investigating a boating accident by checking the salinity of the water. Yes, there was water. Yes, it has a salt content. Was it on the causal chain? Did the motor catch fire due to salt? Even if it did, why measure it? Simply finding that the motor specs included a caution never to be used near salt water and that it was in the Pacific Ocean would be sufficient. But no, it caught fire because of the leaking gas tank, punctured by a fishing gaff. Measuring the salinity of the ocean is superfluous.

A causal chain follows observable departures from ideal operation or condition which can be traced by an envisioned series of causes and effects. Expert witnesses in fire investigation are familiar with this: smoke damage in kitchen is a departure from the ideal condition of the walls, which should be free from much smoke damage. Fire investigator looks further and notes V-pattern near stove top. Looking closer finds a melted aluminum skillet with fried chicken debris at the bottom. All departures of ideal condition or operation. Bingo! And one can envision the sequence of events tracing back to the burned food in a melted pan.

Why measure paint thickness in the back bedroom? Is it related to the scene? Yes. Is it there to be measured? Yes. Is it part of the causal chain? Absolutely not. So why spend time measuring it once one has eliminated it? One has departed from an intelligent path of investigation by the expert witness.

Same with investigating a stove fire. Taking apart the stove and measuring each part and testing the full functionality of every screw, bolt, and resistor is very good for two things: running up a large bill and obscuring the case by a mountain of superfluous detail. Only thing worse would be intentionally presenting false data or conclusions.

This doesn't mean one shouldn't side check one's conclusions or explore other possible causal chains to be sure one has not misinterpretted the evidence. But spending too much time off the path is a waste of resources and money.

It is great for muddying the water though!


Derek Geer
Forensic Engineer/Expert Witness
San Diego, California
www.geers.com

Finding Proximate Causes are only relative

I noticed today that I had been using the term "proximate cause" in reports for some time and wanted to track down the term a bit. Turns out to have quite a history for expert witnesses all the way back to old English law. Francis Bacon took the time to define it--I won't copy that definition here as his definition was somewhat Shakespearean in use of words.

However, here's the thing. The proximate cause is more or less a legal term used by expert witnesses and lawyers meaning that event which lead, ultimately, to the damage. This is a bit misty though. A fire investigator, as an expert witness, would say the proximate cause was the electric furnace failing. This the event which caused the damage or loss. Fair enough.

Then he calls in an engineer, who will take a different level of viewpoint, which is 'what is the proximate cause for this electric furnace catching fire?' He will dissect and analyze and study and may find that the thermal cut out failed. As an expert witness he may say "Ahah! The failure of the thermal cut-out was the event that lead to the loss." Fair enough.

The insurance company will want to subrogate and ask the furnace manufacturer to cough up some portion of the loss. The furnance manufacturer will naturally want to know why the heck the thermal cut out failed. They may acquire the very component or track back to manufacturing dates and component date codes and find that it was not the only one of that date code that had problems. They will then pursue the component manufacturer, say Fujitsu, and subrogate again.

Fujitsu will be unhappy with all this, of course, and have their own expert witness, forensic engineer, or manufacturing engineer do an analysis on why that component had a problem and they may find that there were chemical impurities in the device.

The chemical impurities were due to some failure on the part of, say, Dupont or Dow Chemical. Again proximate cause is being chased at increasing levels of detail.

Obviously, expert witnesses and forensic engineers tend to want to discuss the mechanical causality--the causal chain--the action and mechanical reaction of a series of concatenated events. One may easily find that the chemical impurities were due to an operator failure: end of the mechanical causal chain. But why did the operator fail? Then you are into the mental and emotional possibilities. His wife was leaving him, his child was found using drugs, etc, which so distracted him that he overlooked or flubbed his duties. (There are psychiatrists posing as 'expert witnesses' who could be consulted--but that's a hole we won't dive into.)

The point? Proximate Cause is NOT an absolute (which are unobtainable). It is only
a relative term for the sphere of operation we are talking about. The house should not have burned down, but it did because the furnace as a component of the house
failed. The furnace should not have started a fire, but it did because of the thermal cutout failure as a component of the furnace. The thermal cutout should not have failed... and so on.

Most expert witnesses understand this intuitively, but I realized it was a missing
element in any definition I could find. I also find that I will chase the causal chain as far as I can, beyond my sphere of operation, whenever possible, but can leave it to stand at the sphere of operation I am working in--for me as an expert witness/forensic engineer: one detail level below the fire scene investigator.

Derek Geer
Forensic Engineer
San Diego, California
www.geers.com