As much as jurors resent a witness who lies, you must have inconvertible evidence that someone is out and out lying in order to even suggest it.
Even then, it’s best to let the jurors come to the conclusion that a witness is lying on their own. People are persuaded by their own reasoning far more than by your proffered statements. Use words such as “incorrect” “inaccurate” “not forthcoming” to describe a witness’s testimony as opposed to “lying” or “untruthful.” Let the jurors attach the word “lie” to the testimony – as they will, if your presentation of the witness’s falsehood is effective.
One of the most effective ways to help the jurors get there, is to use the tried-and-true “Chart of Inconsistencies.” As defense, for example, you could bullet on a chart what the plaintiff told Dr. A, the different story he told Dr. B, and the yet more different tale he told at deposition. Or as plaintiff, you could bullet on a chart what defendant told the police, what was discovered in emails, what she swore to in interrogatories. Such a chart alone, since it references facts, has more impact on today’s jurors than your forceful “And he lied!!” ever could.
