Mesa AZ |Witness Testimony In a Personal Injury Case

In most personal injury claims, the plaintiff must prove that the defendant was at fault for the plaintiff’s injury. To prove that the defendant was at fault, the plaintiff must prove that the defendant acted negligently and that his negligence caused the injury.

In Arizona, the defendant will be found negligent if he failed “to act as a reasonably careful person would act under the circumstances.” The defendant’s negligence will be found to have caused the plaintiff’s injury if it helped “to produce the injury and if the injury would not have happened without the negligence.”

At trial, how does the plaintiff actually carry out the task of proving that the defendant was at fault? The plaintiff will need evidence, and evidence will usually be presented to the court through witness testimony.

Witness testimony is presented through a process of examination. The plaintiff’s attorney will call a witness, and the court will swear in the witness. Then, the attorney will ask the witness questions regarding the incident that led to the plaintiff’s injuries, or questions on any other topic relevant to the case. Through the witness’s answers, the jury hears the facts of the case. This is evidence. The attorney may also use a witness to admit other types of evidence to the jury, such as medical records, photographs, and audio recordings.

So, witnesses are clearly an important aspect of any personal injury trial. The rules governing witnesses are found in the Arizona Rules of Evidence. These rules indicate who may testify and what they may testify about. I want to provide an overview of a few of these rules. You can find Arizona’s Rules of Evidence here.

First, who can testify? The Rules say, “Every person is competent to be a witness unless these rules or an applicable statute provides otherwise.” Another provision states, “A witness may testify to a matter only if evidence is introduced sufficient to support a finding that the witness has personal knowledge of the matter. Evidence to prove personal knowledge may consist of the witness’s own testimony. This rule does not apply to a witness’s expert testimony.” The answer to the question of who to testify is: any person, as long as they have personal knowledge of the matter at hand. Notice that the witness himself may provide the evidence of that knowledge, and that the rule does not apply to “expert” witnesses. If a witness is certified as an expert, he or she need not have personal knowledge of the matter.

Next, what can a witness testify about? The Rules state that the subject matter of a witness’s testimony must be relevant. The witness’s testimony will be relevant if: “it has a tendency to make a fact more or less probable than it would be without the evidence; and, the fact is of consequence in determining the action.”

As an example, imagine a case centered on a car accident where the defendant ran a red light. The plaintiff is trying to establish that the defendant was at fault for the accident and the plaintiff’s injuries. The plaintiff calls a witness who saw the accident occur. The witness indicates that he saw the defendant run a red light and then hit the plaintiff. That testimony will surely be relevant, because 1) it makes the fact that the defendant ran a red light more probable; and, 2) that fact will be important in determining that the defendant was at fault.

Finally, can the witness give his or her opinion in testimony? The answer to that question is yes, but pursuant to certain restrictions. The Rules have this to say:

If a witness is not testifying as an expert, testimony in the form of an opinion is limited to one that is:

(a) rationally based on the witness’s perception;

(b) helpful to clearly understanding the witness’s testimony or to determining a fact in issue; and

(c) not based on scientific, technical, or other specialized knowledge within the scope [of the rules regarding expert witnesses].

As you can see, expert witnesses have special privileges. They can give their opinions on many matters not subject to the rules above. However, a witness must be certified as an expert before being able to so testify. Most witnesses are likely to be so-called “lay” witnesses, and they must follow the rules above regarding opinion testimony. An admissible lay opinion might go something like “I saw the accident happen, and it looked to me like the defendant was going really fast before he hit Mike.” However, a lay witness may not give testimony like this: “Based on my knowledge of skid marks at accident scenes, it is my opinion that the defendant was going 74 miles per hour.” The latter is the type of testimony that may only be given by an expert witness.

Of course, there are many more rules regarding witness testimony and evidence in general, and many exceptions to the rules. If you are preparing to bring a personal injury claim, it will be wise to study all of the relevant rules and exceptions. For this reason, it may be beneficial to seek the assistance of an experienced personal injury attorney who is familiar with the application of Arizona’s Rules of Evidence.


This blog should be used for informational purposes only. It does not create an attorney-client relationship with any reader and should not be construed as legal advice. If you or someone you know wishes to seek the help of an experienced personal injury attorney regarding Witness Testimony, or other personal injury matters, call 480.461.5300. Udall Shumway PLC is located in Mesa, Arizona and is a full service law firm. We assist Individuals, families, businesses, schools and municipalities in Mesa and the Phoenix/East Valley.