From time to time, during a car accident injury trial in Missouri, the lawyer for one side or the other tries to use rules from the Missouri driving manual we all had to read prior to taking our Missouri state driving test. Is this manual Missouri traffic law? Depends on what side of the issue you are on. Mostly the use of the manual by the injured party or the defendant lies within the discretion of the trial judge; what reason are they trying to use it, is it relevant, has the legal foundation been established, does it conflict with statutory law, etc…
On such case was the Missouri auto accident lawsuit of Thompson v. Marler, 286 S.W.3d 261 (MO SD Court App. 2009).
Defendant elicited evidence on cross-examination from plaintiff’s witness [….] that a driver’s manual provided that the center turn lane was not to be used “when entering the roadway from a side street.” Marler at 265.
On appeal the case was upheld for reasons not directly related to the above evidence, however, the concurring Judge also wrote in detail about the inconsistency between the manual and Missouri law and that the manual “recommended” a course of action and yet that was used at the trial level to try and prove comparative against the auto accident victim.
[…] witness’s cross-examination when he acknowledged that the Missouri Department of Revenue’s Driver’s Guide (the “driver’s guide”) “recommends” that the center lane not be used for this second purpose for which the lane was designed. No authority has been cited to support the Driver’s Guide recommendation to “not use this lane when entering the roadway from a side street” as a rule of law. In fact, section 300.215–a portion of the Model Traffic Ordinance  — would suggest the contrary. Marler at 268.
As a St. Louis personal injury lawyer having taken several Missouri auto accident cases to trial, I believe the driver’s manual should never had been used in the above manner in the first place. If the manual conflicts with Missouri statutory law then it is a distraction to mislead the jury with no probative value.