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When Can a Trial Lawyer Call a Lie a Lie?

Zachary Winn


  • Model Rule of Professional Conduct 3.4 governs the characterization of testimony and has been adopted without meaningful change in many states.
  • Interpretation of the rule varies by state.
  • The rule applies to all lawyers alike.
  • Lawyers must consult and adapt to local rules.
When Can a Trial Lawyer Call a Lie a Lie?
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The related concepts of disinformation, misinformation, and malinformation are increasingly discussed [login required]. It is perhaps unsurprising, then, that these terms are appearing in legal parlance. Colloquially, the terms refer to lies, though each has a distinct meaning. Whether they can be used to characterize testimony, however, is not clear. State practice regarding the characterization of testimony as a “lie” is inconsistent, requiring lawyers seeking to characterize testimony as “disinformation” or another form of mistruth to think twice before speaking.

The Model Rules of Professional Conduct Are Not Dispositive

Model Rule of Professional Conduct 3.4 governs the characterization of testimony and has been adopted without meaningful change in many states, including those discussed below. Among other things, Rule 3.4 bars a lawyer from asserting personal knowledge of facts in issue and stating a personal opinion as to the credibility of a witness. Characterizing testimony as a “lie” without evidentiary support is an archetypal violation. But states disagree about whether it is permissible to characterize testimony as a “lie” when that conclusion is supported by evidence.

Interpretation of the Rule Varies by State

Fundamentally, states disagree about whether the designation “lie” implicates a personal opinion, and is thus barred by Rule 3.4, or is instead an inference drawn from the facts in evidence, properly the subject of argument. For example, in Florida, it is not improper for counsel to state that a witness “lied” or is a “liar,” so long as such characterizations are supported by the record. But in Colorado, it is improper for a lawyer to use any form of the word “lie” in characterizing for a jury a witness's testimony.

In several states, a lawyer can argue to the jury that they should not believe a witness but cannot call them a “liar.” In some of those states, the term “lie” is treated as sui generis (“in a class of its own”) because the word is innately inflammatory. By that logic, calling a lie a “lie” is impermissible, but lawyers may be permitted to characterize testimony as, e.g., “untrue.” But such a workaround is inconsistent with Rule 3.4. Insofar as the term “lie” is a personal opinion, even when supported by evidence, so too are characterizations invoking other forms of mistruth. Where Rule 3.4 is the basis for a prohibition on the word “lie,” lawyers seemingly must limit arguments to factual description and avoid characterization of testimony entirely. In practice, though, courts have accepted “did not tell you the truth” because, unlike the use of the word “lie,” it does not have same degree of rhetorical power.

There is thus a tension in relying on Rule 3.4’s bar on the assertion of personal knowledge and opinions to prohibit the word “lie.” It is accepted that an argument may include the facts in evidence and inferences drawn therefrom. And the conclusion that testimony is a “lie,” where supported by evidence, is exactly such an inference. Prohibitions on the word “lie” conflate opinion and inference, treating “lie” differently than similar evidence-based statements.

The Rule Applies to All Lawyers Alike

In the states that have adopted it, Rule 3.4 applies to all lawyers, but most cases interpreting the rule involve appeals challenging comments made by prosecutors about defense-witness credibility. So, in discussing the issue, courts have written much about responsibilities unique to the prosecutorial function. It is axiomatic that, while a prosecutor can use every legitimate means to bring about a just conviction, he or she has a duty to avoid using improper methods designed to obtain an unjust result. Some cases describe accusing a witness of “lying” as such an improper method. These cases could be read to suggest that only prosecutors are barred from using the term “lie” to characterize witness testimony. But Rule 3.4 does not distinguish between prosecution or defense, criminal or civil. When a lawyer calls a witness a “liar” in a state that has adopted and is relying on Rule 3.4 to prohibit the term, he or she violates the rule. The nature of the case and the role of the parties are both immaterial.

Lawyers Must Consult and Adapt to Local Rules

In most states, as long as the conclusion is supported by evidence, it is permissible to characterize testimony as a “lie.” But the cases discussed above demonstrate that the rule is not universal. As always, when practicing in a new jurisdiction, lawyers ought to review the case law and consult with local counsel. In a state in which use of the term “lie” is restricted, lawyers cannot rely on their own reading of the rule or the general acceptability of arguing reasonable inferences. Where there is a narrow restriction, “disinformation,” “misinformation,” and “malinformation” may be viable alternatives to “lie.” But where the restriction is broad, those terms and others may also be impermissible.