When an expert witness goes too far in expressing his opinions he may not be permitted to testify.

In the case of, Mutafis v. Markel, Dist. Court, ED Michigan 2013, the court dealt with a police practices expert witness who had very strong opinion about the alleged police conduct.

The court found that the subjective characterizations of the expert and his opinions made his testimony inadmissible as they were too speculative.

The court stated:

Instead, expert offers only a version of the facts using strong adjectives favoring Plaintiff and states an opinion regarding the officers’ conduct that is not helpful to the jury and is purely speculative. His opinions also contain impermissible legal conclusions. For example, expert opines:

• “The police then slammed their patrol unit into the rear of [Plaintiff’s] van.”
• “The criminal and departmental violations committed by the defendant officers Cook and Markel are evident.”
• “In my twenty four years of reviewing law enforcement (use-of-force) cases, this case is the most grievous example of law officer partner collaboration to violate a citizen’s rights.”
• “The first rule of a functioning law enforcement officer in the criminal justice system is honesty. Without honor amongst officers recognizing their role as the, “gateway into the criminal justice system” citizens rights are violated and they get hurt.”
• “This case was not a mistake. It was a disgusting moral failing of both police officers that reflects on a wayward police officer culture.”
• “In review of this case it appears the training of these officers is either amiss or not understood by the defendant officers.”
• “In this case honest and reasonable officer action was almost completely absent.”
• “Officer Markel used excessive force in the application of pepper spray to the citizen that had been beaten down by her and Officer Cook. Only with the arrival of a superior officer did the excessive force cease.”

(Id. Ex. 1.) It is important to stress that these are only examples of the opinions offered by expert that would be improper to admit at trial. There is little, if any, content in the approximate two page “Opinion” section of his report that is admissible under the Federal Rules of Evidence.

In short, this Court agrees with Defendant Cook that the opinions stated in expert report are not admissible at trial pursuant to Federal Rules of Evidence 403, 702, and 703.