Ipse Dixit — When An Expert Witness May Not Be An Expert


Expert witnesses are keys to many personal injury cases. They range from medical experts and crash reconstruction professionals to accountants and automotive mechanics. However, this reliance on the testimony of experts also means their credibility is vital. 

Courts have addressed potential credibility issues through the careful application of a legal doctrine known as ipse dixit. What is ipse dixit? And how can you avoid problems with it? Here's what you need to know.

What Is Ipse Dixit?

This Latin term literally translates to 'he said it himself'. This refers to a statement by a witness that is presented as fact — but which is based solely on the word of the testifier and their perceived authority. 

Why Is Ipse Dixit a Problem?

Expert witnesses, of course, are brought in to provide experience, skills, details, and somewhat esoteric information that laypersons do not have. However, it must be established that there are good reasons for relying on those things. 

Simply saying that one is an expert in a field and that they assert something as fact can be harmful to a fair trial. It risks the jury believing that the fact is established even if it's pseudoscience or outright opinion. 

For example, a self-proclaimed expert in the paranormal may testify that there was a ghost at the scene of an accident, but there's no way to establish their credibility, back up their methodology, or present peer evidence. The jury is asked to simply believe the witness because they claim to be an expert. 

How Do You Avoid Ipse Dixit?

An expert witness must be carefully vetted and selected to provide the strongest basis for their testimony. In general, the witness should be able to back up their professional opinions or reconstructive work with peer-reviewed materials, verifiable credentials, and outside research. 

They should also be an expert in the specific elements to which they will testify. A neurosurgeon may know much about the cardiovascular system, but they wouldn't necessarily be considered an expert in that field. 

Your team will also need to first present the court and the jury with proof of the expert's credentials and expertise. This may seem like an unnecessary bit of administrative work, but it is the only way to really avoid ipse dixit. 

When it comes to the other party's experts, the ipse dixit rules prevent your case from being undermined by unqualified opposing witnesses. You can oppose such witnesses at various stages during the trial process. 

Where to Learn More

Do your potential expert witnesses pass the ipse dixit rules? Do you need to establish more credibility for them? Is your opponent bringing unqualified witnesses? For more information, contact a personal injury lawyer near you.


30 March 2023

Consulting with an Accident and Personal Injury Lawyer

Ten years ago, I was injured in a car wreck while commuting to work. When a driver rear-ended my car, I hurt my back. Unfortunately, I had to undergo a couple of weeks of physical therapy. Even after receiving physical therapy, my back never felt as good as it did prior to the wreck. Have you been injured in a car wreck recently? Consider talking with an experienced accident and personal injury lawyer. This type of attorney can help you decide whether filing a lawsuit is your best course of action to take. On this blog, I hope you will discover the benefits of speaking with an accident and personal injury attorney soon after getting injured in a car wreck. Enjoy!