How Missouri Jury Instructions Shape Your Case

After days of testimony, hours of expert opinions, and two closing arguments pulling in opposite directions, the jury retires to deliberate. But they do not decide your case based on gut feeling alone. The judge gives them a set of written instructions — precise legal statements that define the issues, explain the law, and tell the jury exactly what they must find to return a verdict in your favor.

These instructions are not an afterthought. They are the framework through which every piece of evidence is evaluated. And in Missouri, they follow a mandatory, approved format that shapes trial strategy from the moment a case is filed.

What Are Missouri Approved Instructions?

Missouri uses a standardized set of jury instructions called Missouri Approved Instructions, or MAI. When an MAI instruction exists for a particular issue, the court must use it. Attorneys cannot draft custom instructions on topics that MAI already covers.

This mandatory system serves consistency. A plaintiff in a car accident case in St. Louis receives the same legal instructions as one in Springfield or Kansas City. The same definitions of negligence, the same burden of proof language, the same damages framework.

MAI instructions cover virtually every aspect of civil litigation: negligence, causation, damages, comparative fault, evidence evaluation, and jury procedure. The Missouri Jury Instructions 7th Edition is the current compilation, containing hundreds of approved instructions organized by subject matter.

Why Jury Instructions Matter More Than You Think

Most non-lawyers assume the trial is decided during testimony and closing arguments. In reality, jury instructions often determine the outcome because they define what the jury is allowed to consider and how they must analyze the evidence.

They define the legal standard. The negligence instruction tells the jury precisely what constitutes negligence in Missouri. Without meeting every element in that instruction, the plaintiff cannot recover — regardless of how sympathetic the facts.

They frame the damages question. The damages instructions tell the jury which categories of harm they can compensate: medical expenses, lost wages, pain and suffering, future damages. If a category is not included in the instructions, the jury cannot award it.

They explain comparative fault. In Missouri's pure comparative fault system, the jury must determine each party's percentage of fault. The instruction tells them how to do this and how it affects the damages calculation.

They guide deliberation. Instructions on credibility tell jurors they may consider a witness's demeanor, potential bias, and consistency with other evidence. Instructions on circumstantial evidence explain that the jury can draw reasonable inferences from proven facts.

Key Instructions in Personal Injury Cases

The Negligence Instruction

The core MAI negligence instruction requires the jury to find that:

1. The defendant failed to exercise the highest degree of care (in motor vehicle cases) or ordinary care (in most other cases)
2. The defendant's failure was negligent
3. The defendant's negligence directly caused or contributed to cause the plaintiff's injury

Each element must be proven by a preponderance of the evidence — meaning it is more likely true than not. The instruction does not require certainty, but it requires that the evidence tips the scale.

The distinction between "highest degree of care" and "ordinary care" matters enormously. Missouri applies the highest degree of care standard to motor vehicle operators, which means the defendant is held to a more demanding standard than in a typical negligence case.

The Damages Instruction

The damages instruction tells the jury what they can award. A typical MAI damages instruction covers:

• Medical expenses, past and future
• Lost wages and lost earning capacity
• Pain and suffering, past and future
• Disability and disfigurement
• Loss of enjoyment of life

Each category must be supported by evidence. If no evidence supports future medical expenses — because no doctor testified about the need for future treatment — the jury should not award them, even though the instruction includes that category.

The Comparative Fault Instruction

Missouri's comparative fault instruction asks the jury to assign percentages of fault to each party. The plaintiff's recovery is reduced by their percentage of fault. If the jury assigns the plaintiff 25 percent fault, their damages award is reduced by 25 percent.

The instruction requires the percentages to total 100 percent. This creates a zero-sum dynamic: every percentage point assigned to the plaintiff comes off their recovery.

Credibility Instructions

The jury receives instructions on how to evaluate witness credibility. These instructions tell jurors they may consider:

• The witness's opportunity to observe the events
• The witness's ability to remember and communicate
• The witness's interest in the outcome
• The witness's bias or prejudice
• Whether the witness's testimony is consistent with other evidence
• Whether the witness has made prior inconsistent statements

These instructions give the jury permission to discount testimony they find unreliable — which is why witness preparation and consistent testimony are so important.

How Instructions Shape Trial Strategy

Experienced attorneys do not wait until the end of trial to think about jury instructions. Instructions inform strategy from the beginning.

Case theory alignment. Your attorney structures the entire case to satisfy the elements of the applicable MAI instruction. Every witness, every exhibit, every question is designed to check a box in the instruction framework.

Evidence selection. Knowing which damages categories the instruction covers guides decisions about which experts to retain, which records to obtain, and which testimony to emphasize.

Jury argument. In closing argument, your attorney walks the jury through the instructions element by element, connecting each element to specific evidence they heard during trial. This technique — sometimes called "instructing the argument" — gives the jury a clear roadmap for deliberation.

Verdict form design. The verdict form mirrors the instructions. In a comparative fault case, the form asks the jury to state the total damages and each party's percentage of fault. The design of this form can affect how jurors think about the numbers.

Instruction Conferences and Disputes

Before the jury deliberates, the attorneys and judge meet to finalize the instructions. This instruction conference is one of the most important procedural moments in the trial.

Each side submits proposed instructions. Disputes arise when attorneys disagree about which instructions should be given, how they should be worded, or whether the evidence supports a particular instruction.

Common disputes include:

• Whether the evidence supports a comparative fault instruction
• Whether the plaintiff has presented sufficient evidence of future damages
• Whether a punitive damages instruction is warranted
• Whether a particular MAI instruction or a non-MAI instruction should be used

The judge resolves these disputes, and each ruling is preserved for potential appeal. An incorrect jury instruction is one of the most common grounds for appellate reversal.

FAQ

Can the jury ask questions during deliberation?

Yes. If the jury has questions about the instructions or the evidence, they can submit written questions to the judge. The judge, after consulting with both attorneys, sends a written response. Common questions involve clarifying legal terms or requesting that testimony be read back.

What happens if the judge gives a wrong instruction?

An incorrect jury instruction can be grounds for appeal. If the appellate court determines that the wrong instruction was given and that the error likely affected the outcome, the case may be reversed and remanded for a new trial. This is why objections during the instruction conference must be clearly stated and preserved.

Do jurors get to keep the written instructions?

Yes. The jury receives a written copy of the instructions to reference during deliberation. This is why the precise wording matters — jurors read and re-read the instructions as they work through the verdict form.

How long do jury instructions take to read?

Reading jury instructions typically takes 30 minutes to an hour, depending on the complexity of the case. In a straightforward car accident case, the instructions may be relatively brief. In a complex medical malpractice case with multiple defendants and counterclaims, the instructions can be extensive.

Can I learn what instructions will be given before trial?

Your attorney will know which MAI instructions apply to your case and will prepare proposed instructions well before trial. Discussing the instructions with your attorney helps you understand what the jury will be asked to decide and how the evidence connects to each element.

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This article is for informational purposes only and does not constitute legal advice. Every case is different. Contact OTT Law at (314) 794-6900 for a free consultation specific to your situation.