Expert witnesses are all but necessities for a self-defense trial, either in criminal or civil court.
Eugene O. Jamison had a degree in dairy science. He knew everything that should be in milk, what should not be in milk, and how milk should be processed, stored and served. He never milked a cow in his life. This was much to the amusement of his father-in-law, who milked cows every day. Each was a milk expert in his own way. Each could testify about milk … depending on what sort of evidence was wanted.
Juries are selected for their complete ignorance of the technical evidence in the cases before them, so experts are required to educate them. Renowned defense attorney F. Lee Bailey once argued a poisoning case and desperately tried to keep a chemistry professor on the jury in hopes that the man would understand the evidence and educate the rest of the jury. Bailey, unfortunately but predictably, failed, but the case underscores the importance of expert testimony in open court and at least helps explain why expert witnesses are increasingly necessary in the judicial system. Prosecutors worry about the “CSI effect.” After de- cades of TV shows about forensic science, juries are reluctant to convict without it, and the converse is also true.
Jurors in a mock trial saw a prosecution fingerprint expert testify, and most were ready to convict on his testimony alone. When a defense expert was added to explain how fingerprints were gathered and examined, there was a significant reluctance to convict.¹ When the only expert testifying is a cheerleader for the prosecution, conviction will be the result. Thus, any self-defense “insurance” policies that do not provide funds for experts are inadequate. Experts can be from many fields. I have employed private investigators to search for bullets with metal detectors.
These investigators could be introduced in court as "fact witnesses," which are easier to introduce than expert witnesses. In one case, an unhappy (and very possibly insane) ex-wife tried to steal her ex-husband’s ATV, and the ex-husband fired a warning shot from a shotgun. Warning shots are almost never advisable.² In this case, the lady fled to the sheriff’s office and gave an imaginative account of buckshot whistling past her head and kicking up dirt on her and a companion.³ I hired an investigator, who took a metal detector to the spot my client pointed out and found a load of buckshot. I knew what the prosecutor would argue and sent the investigator back to scan the entire yard and place every bit of metal in a clear plastic bag. He testified to finding these objects. When the prosecutor claimed that my client planted the buckshot, I jingled the bag of scrap metal and demonstrated that buckshot was found in only one spot.
In another case, an architect was employed to diagram a room. A ballistics expert then testified as to the track of the defensive bullet. This demonstrated where my client was and where the intruder was at the time of the shooting. This supported my client’s testimony.
I have used a gunsmith to tell me if a gun was working properly. In one case, it was working properly ... and that was not what I wanted to hear. In any field, there are those who will testify convincingly to whatever is desired. On one occasion, Jackson County, Missouri, judges declared they would no longer take evidence from a workmen’s compensation insurance company doctor who declared that every injury was "psychosomatic." Using such “experts” who can be bought gives an attorney a certain reputation that makes his or her legitimate claims questionable.
A judge has broad authority to admit experts in fields he or she knows nothing about. Attorneys must convince the judge to exercise his or her “gatekeeper” function to allow an expert to testify. The first obstacle is to convince the judge that such a field of study exists. Outside of routine medical and forensic testimony, this can be quite a struggle. In one case, a defendant emptied nearly the entire magazine from an SKS into a threat. The prosecution argued that this was overkill and evidence of murder.⁴ The defense named a retired police trainer to testify as to the human dynamics of a gunfight — specifically that “rapid-fire syndrome” results in emptying a weapon into a threat.
The prosecution denied that there was any such field of study and then named a retired highway patrolman as its expert in the same field. This caused some amusement in the defense expert, who knew that the highway patrolman, early in his career, had emptied his .357 Magnum into a threat who was later found to have been armed with a toy.⁵ The judge demanded to see an appellate opinion from his state ruling such evidence admissible. The acts of other courts would not do. No judge likes to be first in such a field.


The basis for an expert to take the stand was laid out in the 1993 case of Daubert v. Merrell Dow Pharmaceuticals Inc.:
• The testimony must be scientifically valid and reliable.
• The testimony must be based on more than subjective belief or unsupported speculation.
• The methodology should include conclusions that can be and have been tested.
• The methodology should be subject to peer review and publication.
• The methodology should have some known or potential error rate.
• There should be standards maintained in the discipline.
• The methodology should be generally accepted in the scientific community.⁶
This was a U.S. Supreme Court decision, and state court standards may vary. These standards presume a science in which degrees are granted; experts in practical matters, such as milking a cow, will be more difficult to introduce.
The expert’s resume should be requested along with any articles or books he or she has written and other cases in which he or she has testified. During such a vetting process, it may be found that an "expert" has changed his or her opinions from case to case in order to fit his or her paychecks.
The expert’s training must be examined. Many forensic labs have experts whose preparation consisted of little more than on-the-job training. Some labs do not periodically requalify their experts, and some others do not double-check an expert’s work; in some, the double-check is perfunctory. Mistakes happen. An FBI agent was charged with drunk driving following an accident.
Upon investigation, it was determined that his blood test was confused at the hospital with another party’s test.⁷
There is even the occasional report of an expert who invented test results to match the desired result.
Then there are genuine differences of opinion. The excellent movie The Trial of Bernard Goetz is taken directly from the trial transcripts. An expert for the prosecution testified that something is absolutely positively and to a reasonable scientific certainty true. An expert for the defense said that it is absolutely positively and to a reasonable scientific certainty not true. The jury was supposed to decide between them. Such a decision will probably go to the expert who explains technical matters in a manner the average person can understand.
Then there are junk sciences. For decades, people were put in prison based on hair comparisons. People shed hair like dogs shed fur. Hair found at a crime scene was compared to a suspect and the suspect went to prison. Ironically, hair-evidence textbooks were emphatic that all hairs on a person were different from every other hair. The texts were clear that it is not possible to scientifically state a suspect’s hair matches the crime-scene hair. Hair experts got around this by saying the hairs were “consistent.” This means that they are both the same color, fine or coarse, curly or straight. Prosecutors presented the term “consistent” as if it meant “match.”⁸
Innocent people went to prison. Fortunately, DNA demonstrated that some of these convictions were wrong. Someone finally read the hair-comparison textbooks and got his or her own expert.
The art-appreciation means to conviction finally went the way of phrenology.⁹
Photographs and videos are common items of evidence, but cellphones and security cameras often give indistinct representations of events. Self-defense frequently happens at night, further blurring these events. This leaves such videos open to interpretation.
One nighttime video was the basis for a charge of brandishing a firearm. An expert heightened the contrast in the video to show that the defendant did not have a gun. Prosecutors still claimed to see a gun. They did, however, offer an exceptionally good plea bargain.
There are experts in the reconstruction of shooting incidents. 10This field requires expertise in blood-spatter analysis, ballistics, wounds, firearms and human reactions under stress. As such, a single expert may not be enough. In the copyright page of Shooting Incident Reconstruction, it warns: “Knowledge and best practices in this field are constantly changing. As new research and experience broaden our understanding, changes in research method, professional practices or medical treatment may become necessary.”
This is a nice way of saying that some things experts absolutely, positively and to a reasonable scientific certainty know are true … are not. So be certain to check whether an "expert" has continued his or her education.
Kevin L. Jamison is an attorney in the Kansas City Missouri area concentrating in the area of weapons and self-defense.
Please send questions to Kevin L. Jamison 2614 NE 56th Ter Gladstone Missouri 64119-2311 KLJamisonLaw@ earthlink.net. Individual answers are not usually possible but may be addressed in future columns.
This information is for legal information purposes and does not constitute legal advice. For specific questions you should consult a qualified attorney.


(1) Garrett, Brandon L., Autopsy of a Crime Lab (University of California Press, Oakland, CA, 2021), 114. (2) See Jamison, K. L., “Warning Shots,” Concealed Carry Magazine, August/September 2011, at 60 et seq. (3) Ballistically impossible. (4) The prosecution later argued that the defendant’s wood-frame garage apartment was the equivalent of a “World War II bunker.” (5) The trooper retired after a long career with a contract to testify to any matter useful to the state. (6) Garrett, Autopsy of a Crime Lab, at 124. (7) Wittman, Robert K., Priceless (Broadway Paperbacks, NY, 2010), at 45 et seq. (8) Matching fingerprints to those left at crime scenes has proven to have its own problems. For mistakes, see Garrett, Autopsy of a Crime Lab, a critical text for lawyers dealing with crime labs. (9) An old junk science that predicted criminal inclinations by examining the bumps on a suspect’s head. (10) See Hueske, Edward E., Practical Analysis and Reconstruction of Shooting Incidents (CRC Press, Boca Raton, FL, 2006), and Haag and Haag, Shooting Incident Reconstruction (Academic Press, San Diego, CA, 2011).