Relevancy and reasons for excluding relevant evidence - Ulti...

Learning Outcomes

This article explains how relevancy and the ultimate issue rule operate on the MBE, including:

• how to distinguish logical from legal relevance and spot when evidence actually affects a fact of consequence;
• how courts conduct Rule 403 balancing and typical fact patterns where otherwise relevant evidence is excluded as unfairly prejudicial, confusing, or cumulative;
• how policy-based exclusions and limiting instructions interact with relevancy and do not conflict with the ultimate issue rule;
• how the ultimate issue rule developed, its modern scope under Rule 704(a), and why most ultimate-issue opinions are now permitted;
• how to differentiate between permissible lay opinions based on perception and impermissible lay testimony that simply states legal conclusions;
• how to evaluate expert qualifications, bases, and methods when experts give opinions that touch negligence, defect, causation, or other ultimate civil issues;
• how Rule 704(b) restricts expert mental-state testimony in criminal cases, especially regarding intent, insanity, and mens rea elements;
• how to analyze MBE question stems that mix hearsay, relevance, and opinion testimony, and choose the answer that identifies the correct exclusionary rule;
• practical strategies for organizing exam answers, including stepwise analysis of witness type, opinion rule, Rule 704, and Rule 403.

MBE Syllabus

For the MBE, you are required to understand the principles governing the admissibility of evidence, with a focus on the following syllabus points:

• The definition and scope of relevancy in evidence law (logical and legal relevance).
• The main policy reasons for excluding relevant evidence (e.g., unfair prejudice, confusion, waste of time).
• The ultimate issue rule and its application to lay and expert opinion testimony.
• Specific limits on expert testimony regarding a criminal defendant’s mental state (Rule 704(b)).
• The relationship between the ultimate issue rule, Rule 403, and other exclusionary or limiting rules (e.g., hearsay, limited admissibility).

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.

1. Which of the following is most accurate regarding the ultimate issue rule?
   1. Expert witnesses may always state an opinion on the ultimate issue.
   2. Lay witnesses may never state an opinion on the ultimate issue.
   3. Expert witnesses may state an opinion on the ultimate issue, except as to a criminal defendant’s mental state.
   4. Relevant evidence is always admissible, regardless of the ultimate issue.
2. A defendant is on trial for murder. The prosecution’s expert psychiatrist testifies, “In my opinion, the defendant had the intent to kill.” Is this testimony admissible?
   1. Yes, because it helps the jury decide intent.
   2. Yes, because experts may always testify to the ultimate issue.
   3. No, because experts cannot state an opinion as to whether the defendant had the required mental state.
   4. No, because expert testimony is never allowed on intent.
3. Which of the following is a valid reason for excluding relevant evidence?
   1. The evidence is cumulative.
   2. The evidence is highly prejudicial.
   3. The evidence may confuse the jury.
   4. All of the above.

Introduction

Relevancy is the threshold requirement for the admissibility of evidence. However, not all relevant evidence is admitted. The rules of evidence also exclude relevant evidence for policy reasons, including the risk of unfair prejudice, confusion, or waste of time. The ultimate issue rule addresses whether witnesses, especially experts, may give opinions on the precise legal question the jury must decide. Understanding these principles, and how they interact, is essential for MBE success.

Relevancy: The Basic Standard

Evidence is relevant if it tends to make a fact of consequence in the case more or less probable than it would be without the evidence. The Federal Rules combine two ideas—materiality and probativeness—into this single concept.

Key Term: Relevancy
Evidence is relevant if it has any tendency to make a fact of consequence to the determination of the action more or less probable than it would be without the evidence.

Another way to see this is to separate logical and legal relevance:

Key Term: Logical Relevance
Logical relevance means the evidence has some rational tendency—however slight—to make a fact of consequence more or less likely than it would be without the evidence.

Key Term: Legal Relevance
Legal relevance asks whether logically relevant evidence should nevertheless be excluded because its probative value is substantially outweighed by dangers such as unfair prejudice, confusion, or waste of time (Rule 403).

Two additional points that commonly appear on the MBE:

• Direct vs circumstantial evidence: Both can be relevant. Direct evidence (e.g., “I saw D punch V”) directly proves a fact. Circumstantial evidence (e.g., “I saw D running away with bloody knuckles”) requires an inference. The rules do not prefer one over the other.
• Low bar: Relevance is a very low threshold. Almost any logical connection will satisfy Rule 401; most fights are about Rule 403 (legal relevance), not about basic relevance.

Reasons for Excluding Relevant Evidence

Even if evidence is logically relevant, it may be excluded under Rule 403 if its probative value is substantially outweighed by certain dangers.

Key Term: Policy Exclusion
A policy exclusion is a rule that excludes otherwise relevant evidence for reasons such as unfair prejudice, confusion, or waste of time, to further fairness, reliability, and efficiency in trials.

The classic Rule 403 dangers are:

• Unfair prejudice (e.g., inflaming the jury’s emotions).
• Confusing the issues or misleading the jury.
• Undue delay.
• Wasting time.
• Needless presentation of cumulative evidence.

Key Term: Unfair Prejudice
Unfair prejudice is an undue tendency to suggest a decision on an improper basis, typically an emotional one, rather than on the evidence and the law.

On the MBE, pay close attention to the modifier “unfair.” Evidence is almost always prejudicial in the sense that it hurts one side; Rule 403 focuses on prejudice that is unfair and substantially outweighs probative value. Also note:

• “Unfair surprise” is not a Rule 403 category.
• The standard is “substantially outweighed”—a strong tilt toward exclusion is required.

Sometimes, instead of excluding evidence entirely, the court admits it but restricts how the jury may use it.

Key Term: Limited Admissibility
Limited admissibility occurs when evidence is admitted for one permissible purpose or against one party, but the jury is instructed not to consider it for other purposes or against other parties (Rule 105).

Example: A prior conviction may be admissible to impeach a witness’s credibility but not as proof that the witness committed the current offense. The judge gives a limiting instruction telling the jury exactly how the evidence may—and may not—be used.

The ultimate issue rule operates against this backdrop: even if an opinion goes to the heart of the case, it must still clear the hurdles of relevance, Rule 403 balancing, and any specific prohibitions such as Rule 704(b).

The Ultimate Issue Rule

The ultimate issue rule governs whether a witness, especially an expert, may give an opinion that directly addresses the legal question the jury (or judge in a bench trial) must decide, such as “Was the defendant negligent?” or “Was the contract unconscionable?”

Historically, courts often barred opinion testimony “on the ultimate issue.” The Federal Rules rejected that broad ban.

Key Term: Ultimate Issue Rule
Under the modern rule, opinion testimony is not objectionable merely because it directly addresses an ultimate issue, but in criminal cases an expert may not state an opinion about whether the defendant had a mental state or condition constituting an element of the crime or of a defense (Rule 704).

So, the modern framework is:

• In civil cases, both lay and expert opinions may touch the ultimate issue if they otherwise satisfy the opinion rules and are helpful.
• In criminal cases, lay opinions may address the ultimate issue if Rule 701 is satisfied, but experts face a specific bar: they cannot opine directly on whether the defendant had the required mental state (e.g., intent, knowledge, malice, premeditation, insanity standard).

This limited carve‑out in criminal cases is often tested.

Application to Lay and Expert Witnesses

Opinion testimony is governed by different rules for lay and expert witnesses.

Lay Opinion and the Ultimate Issue

Lay witnesses generally testify to facts, not conclusions. However, the Rules allow limited lay opinion when it is practical and helpful.

Key Term: Lay Opinion
A lay opinion is testimony by a non‑expert that is (1) rationally based on the witness’s perception, (2) helpful to understanding the testimony or determining a fact in issue, and (3) not based on scientific, technical, or specialized knowledge (Rule 701).

Common permissible lay opinions include:

• “He looked drunk.”
• “The car was going very fast.”
• “She seemed very angry.”
• “The handwriting looked like the defendant’s,” if based on prior familiarity.

These may implicitly touch the ultimate issue (e.g., intoxication in a DUI case). That is allowed so long as the opinion is grounded in personal observation and is helpful.

What lay witnesses cannot do:

• Use specialized knowledge (e.g., diagnosing schizophrenia, calculating stopping distances using engineering formulas).
• Give bare legal conclusions, such as “He was negligent,” “That was a binding contract,” or “The officer used excessive force.” These tend not to be “helpful” because they simply tell the jury what result to reach.

The MBE often tests whether a lay opinion is based on firsthand perception and whether it crosses the line into legal conclusion or expert territory.

Expert Opinion and the Ultimate Issue

Experts operate under Rules 702–704. They may offer specialized opinions that assist the jury in understanding the evidence or deciding a fact.

Key Term: Expert Opinion
Expert opinion is testimony by a qualified expert based on sufficient facts or data and reliable principles and methods, applied reliably to the case, that will help the trier of fact understand the evidence or determine a fact in issue (Rule 702).

In most cases, experts may give opinions that directly address an ultimate issue.

• Design‑defect case: “In my opinion, the product was defectively designed.”
• Medical malpractice case: “In my opinion, the surgeon’s conduct fell below the accepted standard of care.”

These opinions are allowed despite going directly to negligence or defect, because they assist the jury with technical matters.

However, two important limits remain:

1. The opinion must still be helpful and within the expert’s field, not merely a legal conclusion wrapped in expert clothing.
2. In criminal cases, Rule 704(b) imposes a special restriction on mental‑state testimony.

Key Term: Expert Testimony on Ultimate Issue
In criminal cases, an expert may not state an opinion about whether the defendant did or did not have the mental state or condition constituting an element of the crime or of a defense; the expert may describe diagnoses and symptoms but may not directly answer the legal mental‑state question (Rule 704(b)).

So in a federal criminal case:

• Allowed: “The defendant has schizophrenia,” “He experiences delusions,” “He has difficulty distinguishing reality from hallucinations,” “People with this disorder often cannot appreciate the wrongfulness of their acts.”
• Not allowed: “At the time of the offense, the defendant could not appreciate the wrongfulness of his acts,” or “He lacked the intent to kill.”

The line is between explaining the medical or psychological facts and directly stating the legal mental‑state conclusion.

Worked Example 1.1

A defendant is charged with arson. The prosecution calls a fire investigator, who testifies, “In my opinion, the fire was intentionally set.” Is this testimony admissible?

Answer:
Yes. The expert may give an opinion that the fire was intentionally set, as this helps the jury decide a fact in issue—whether the fire was accidental or deliberate. The expert is not stating whether the defendant had the required mental state, only that the fire’s origin was intentional. Rule 704(b) is not triggered because the opinion addresses the fire, not the defendant’s mental state.

Worked Example 1.2

In a murder trial, the defense calls a psychiatrist who testifies, “The defendant lacked the capacity to form intent to kill.” The prosecutor objects. Is the testimony admissible?

Answer:
No. In a criminal case, an expert may not state an opinion about whether the defendant did or did not have the mental state or condition constituting an element of the crime or a defense. Saying the defendant “lacked the capacity to form intent to kill” is a direct opinion on the legal element of intent. The psychiatrist may instead testify about diagnoses, symptoms, and general effects on decision‑making, leaving the ultimate mental‑state determination to the jury.

Worked Example 1.3

In a products‑liability case, the plaintiff calls an engineer who testifies, “In my opinion, the ladder failed to meet accepted safety standards in the industry and posed an unreasonable risk of collapse.” The defense objects that this invades the province of the jury by addressing the ultimate issue of defect. How should the court rule?

Answer:
Overrule the objection. Expert testimony that a product failed to meet industry safety standards and posed an unreasonable risk is the type of technical opinion that helps the jury decide whether the product was defective. Under Rule 704(a), an opinion is not objectionable simply because it directly addresses an ultimate issue. The testimony is framed in technical terms, not as a bare legal conclusion such as “the product was defective as a matter of law.”

Worked Example 1.4

In a criminal assault trial, the prosecution calls a forensic psychologist who testifies, “Based on my evaluation, the defendant knew that his conduct was wrong when he attacked the victim.” The defense objects. Is the testimony admissible?

Answer:
No. This is a criminal case, and the expert is giving a direct opinion on whether the defendant “knew his conduct was wrong”—the precise mental‑state element for an insanity defense under many statutes. Rule 704(b) forbids expert opinions stating whether the defendant did or did not have a mental state or condition that constitutes an element of the offense or a defense. The psychologist may describe diagnoses and symptoms but cannot reach that ultimate mental‑state conclusion.

Worked Example 1.5

In a robbery trial, a bystander testifies, “When I saw the defendant, he looked terrified and confused, like he didn’t know what he was doing.” The defense objects that this is an improper opinion. How should the court rule?

Answer:
Overrule the objection. This is lay opinion under Rule 701: it is rationally based on the witness’s own perception of the defendant’s appearance and behavior, and it may help the jury understand what the defendant was like at the time. The witness is not using specialized knowledge or legal terms; he is simply describing observed behavior in everyday language. The fact that the opinion may bear on the ultimate issue of intent does not make it inadmissible.

The Ultimate Issue Rule and Other Exclusionary Rules

The ultimate issue rule does not operate in isolation. Even if an opinion is not barred by Rule 704(b), it may still be excluded or limited under other rules:

• Rule 403: An ultimate‑issue opinion may be excluded if its probative value is substantially outweighed by unfair prejudice or potential to mislead. For example, a highly inflammatory expert statement that portrays the defendant as a “born killer” could be excluded under Rule 403 even if it does not directly state the defendant’s mental state.
• Hearsay: An expert’s opinion may be based on otherwise inadmissible hearsay if such information is reasonably relied upon in the field. But the hearsay on which the opinion is based is not automatically admissible for its truth; it may come in only if its probative value in evaluating the expert substantially outweighs its prejudicial effect.
• Limited admissibility: The court may admit an opinion for a specific, limited purpose and give a limiting instruction to the jury.

Exam Warning

On the MBE, do not confuse the ultimate issue rule with the general rule against legal conclusions. Opinions are not inadmissible just because they go to the ultimate issue. They are inadmissible when they (1) violate Rule 704(b) in a criminal case, (2) are not helpful under the opinion rules, or (3) fail other admissibility requirements such as Rule 403 or hearsay rules.

Practical Exam Approach

When you see an opinion that touches the core question of the case, work through these steps:

1. Identify the witness type. Lay or expert?
2. Apply the correct opinion rule.
   • Lay: Rule 701—perception‑based, helpful, non‑specialized.
   • Expert: Rule 702—qualified expert, reliable methods, helpful.
3. Ask whether it directly addresses an ultimate issue.
   If yes, remember that is not a problem by itself.
4. If criminal and expert, apply Rule 704(b).
   Does the expert directly state whether the defendant did or did not have the required mental state? If so, it is barred.
5. Always check Rule 403.
   Is the evidence so prejudicial or confusing that its probative value is substantially outweighed?

Revision Tip

If a question asks whether an expert can testify that the defendant “was insane,” “could not appreciate the wrongfulness of his acts,” or “had intent to kill,” focus on whether the case is criminal and whether the expert is directly addressing the statutory mental‑state element. In that situation, Rule 704(b) generally bars the opinion.

Key Point Checklist

This article has covered the following key knowledge points:

• Evidence is relevant if it has any tendency to make a fact of consequence more or less probable (logical relevance).
• Even relevant evidence may be excluded under Rule 403 if its probative value is substantially outweighed by dangers such as unfair prejudice, confusion, or waste of time (legal relevance).
• Policy exclusions and Rule 403 operate alongside, not instead of, the ultimate issue rule.
• The ultimate issue rule allows opinion testimony that directly addresses an ultimate issue, but expert opinions directly addressing a criminal defendant’s mental state element are barred by Rule 704(b).
• Lay opinions must be rationally based on perception, helpful, and non‑specialized; they cannot simply state legal conclusions.
• Expert opinions must be helpful, grounded in reliable methods, and within the expert’s field, and in criminal cases cannot directly answer whether the defendant had the required mental state.
• Courts can use limited admissibility and limiting instructions to control how evidence that might be misused by the jury is considered.

Key Terms and Concepts

• Relevancy
• Logical Relevance
• Legal Relevance
• Unfair Prejudice
• Policy Exclusion
• Ultimate Issue Rule
• Expert Testimony on Ultimate Issue
• Lay Opinion
• Expert Opinion
• Limited Admissibility