When is a medical expert needed to prove causation in a personal injury case?

Personal Injury Lawyer - Proving your case through medical experts.

In cases where the injuries complained of are of a complex nature and are not readily objective in nature, a Plaintiff must present evidence through a skilled professional so as to provide a causal connection between the injury complained of and the accident in question.  See Reed v. Scott, 820 P.2d 445 (Okla. 1991); Matchen v. Mcgahey, 445 P.2d 52, 57 (Okla. 1969). An expert’s testimony must show that the accident in question was the probable cause of injury.  Testimony showing that a specific accident was possibly the cause of an injury is not enough to show causation. 

In Cohenour v. Smart, 240 P.2d 91, 93 (Okla. 1951), the Oklahoma Supreme Court explained:

Testimony as to possibility is said to mean testimony in which the witness asserts that the accident or injury ‘may have’ or ‘could have’ caused, or ‘possibly did’ cause the subsequent physical condition, or that a given physical condition ‘might have’, ‘may have’ or ‘could have’ caused, or ‘possibly did’ result from a previous accident or injury – testimony, that is, which is confined to words indicating the possibility or chance of the existence of the causal relation in question, and which does not include words indicating the probability or likelihood of its existence.


Cohenour, at 93.  The Supreme Court went on to explain that, “[W]here the evidence of the plaintiff does not show by expert testimony and all the surrounding facts and circumstances that the injury could have been caused by and was the probable result of the accident, then the plaintiff has not established sufficient facts to make out a cause of action.”  Id.  The Court concludes that expert testimony must show that an injury was definitely the cause of a certain accident.  If the expert testimony only shows that there is a possibility that a plaintiff’s injuries might have been caused by the accident at issue, then that testimony is not enough to prove causation.  In reaching their conclusion, the Court cites Hunt v. Armour & Co., 136 S.W. 2d 312:

It is now settled that, in matters where the evidence does not exclude all other causes and in which no layman could know or have any reasonable basis for an inference as to cause, opinions of doctors that a certain occurrence or condition might, could, or would produce a certain result is no more than an assurance that such a result was scientifically possible, and does not alone constitute substantial evidence that such occurrence or condition did cause it.