In the practice of law, determining who is lying and who is telling the truth is of critical importance in a variety of contexts.

Let’s begin with client intake. An ethical plaintiff’s lawyer needs to be vigilant in new client intake to weed out those people who seek to use the legal system as a tool of unjust enrichment. Credibility assessments are a vital tool in the screening process. To the best you are able, you need to be able figure out who’s telling the truth and who is not. For the cynical reader, this is necessary, not only because it’s the right thing to do, but because you’ll be facing a skilled adversary in defense counsel, equally capable of sniffing out a bogus claim, and you’re not going to make money when your clients lies are exposed down the road and their case falls apart. (It’s also the right thing to do.)

On the other side of the aisle, defense counsel cannot properly defend their clients who’ve been accused of wrongdoing if they uncritically accept their client’s protestations and denials. The client will be ultimately far better served if the truth, warts and all, is known to defense counsel sooner rather than later. There’s nothing like seeing your client exposed in a lie while under oath, knowing full well how the value of plaintiff’s case just skyrocketed accordingly. If counsel had known the truth beforehand, he would have been able to give advice beforehand (like “don’t lie under oath”), including the opportunity to settle a matter quietly if the liability and/or damage risk is too high. Lie detection is a critical skill in these initial client intact evaluations for civil plaintiff and defense attorneys alike.

After intake, the ability to suss out liars remains a critical skill to litigators all throughout the course of litigation. The ability to assess the credibility of witnesses is essential, whether it be during an interview, in deposition, or on the stand at trial. Done properly and early enough, such assessments factor into when or whether you might put a witness on the stand, tear apart a lying witness, or use their statements at all to advance your client’s case. It is unsurprising then that good lawyers develop and refine their own internal lie detection mechanisms, and endlessly hone techniques for doing so over a lifetime of practice.

Studies have shown however, that however much people think they can spot a liar, evidence suggests that people are not particularly good at it, neither intuitively nor through the development of a lie detector skill set. Studies have shown that, statistically, people aren’t nearly as good as detecting a lie, absent external evidence exposing such lies, as we all inherently think we are, lawyers included.

This is why good lawyers must develop techniques for proving lies as lies. These are the essential tools of litigation itself. If a statement can be shown to be false, for example, then a juror doesn’t have to rely on their (possibly very flawed) instincts for assessing the credibility of the witness providing the statement. Consider: A criminal defendant says he didn’t rob that bank, that he wasn’t even there that day, and yet here’s this security video that very plainly shows the same defendant waving a gun in a teller’s face. Or a civil defendant says he “doesn’t have a racist bone in his body” and then here’s a video of him speaking at a KKK rally. You get the point. The video proves the defendant a liar. No internal instinct for lie detection required.

It is important to note two things about the various cautions about human fallibility in detecting lies. First, reliable or not, people still tend to believe, to a greater or lesser extent, that they can spot a liar. That internal sense exists and people tend to rely on it.

The second, more important note is that the statistical disparity between when people think they know someone’s lying and when they actually are can be explained in part by a class of talented liars who escape detection. In other words, it is not to say that people simply can’t spot liars at all. People definitely can. What people can readily do—and this can be enhanced and improved with practice—is spot bad liars. There are plenty of signs, of “tells,” that bad liars reveal that allow a keen observer to properly assess the truthfulness of a given statement.

In my nearly two decades of practicing law, I have both developed and refined my own internal lie detector and also come to terms with the fact those studies are probably correct—our instincts alone are probably neither sufficient for sussing out liars nor advisable to be relied upon exclusively. This is why it is critical to develop skills at exposing lies through proof. And one of the best ways to prove a statement untrue is with documentary evidence.

Other witness testimony can also discredit another witness’ statements, but this type of evidence is somewhat more fraught and relies, at least in part, upon a juror’s flawed intuitions about who’s telling the truth—the very problem we’re trying to avoid by providing proof. If it’s just one witness’s word against another’s—colloquially, a “swearing contest” or “he said/she said”—determining who’s telling the truth and who is not is inherently challenging. The outcome often comes down to who appears more credible, and we’re right back into the ‘flawed instincts’ soup again. Documentary evidence (including photographs and video) is often a much stronger order of proof for refuting a witnesses lies.

This all goes to say that I don’t have any magic formula to share with you for how to spot a liar. There are ways to improve your lie-detection abilities, and there are great ways to prove a statement a lie, but no magic formula.

In my years of practice, however, I have been able to identify some near universal truths about lies and liars, and these have some bearing on this weekend’s news about the Mueller team having obtained (some time ago) thousands of Trump transition team emails from the GSA.

My first observation about liars, gleaned over years of taking note of such things, is that lies are extremely utilitarian. This is one thing in common that most all lies share. Lies are nearly always a means to an end, and told as a utility to accomplish some goal.

[Note: This is a somewhat obvious observation, admittedly, that might perhaps not be worth mentioning but for a certain orange-hued president* of recent vintage. Donald Trump is a prominent exception to this rule. He lies so frequently, and so seemingly unnecessarily at times, that its not accurate to say that his lies are utilitarian. Some very obviously are, but often times, he seems to lie just for the lie’s own sake. There are some pathologies at work in Trump’s relationship with the truth, the diagnosis of which are above my pay-grade. It’s enough to recognize the phenomenon. I’ll leave it to other learned disciplines to diagnose the root causes.]

Far more significant than the utilitarian aspect of people’s lies, is one other element I have found in common with nearly all liars (particularly in statements under oath—in a deposition or on the witness stand): people lie when they think they can get away with it.

That it. People lie when they think they can get away with it, when they believe they can lie without consequence. This is not to suggest that people lie merely because they can get away with it. (That’s more like Trumpian lying, though he’s even worse than that. He frequently lies even when it’s glaringly evident he’s not telling the truth, or when the statement is readily capable of being shown to be false.) I’m not saying that people lie every time they think they can get away with it. Not at all. I’m saying “believing they can get away with it” is one element shared nearly universally by all liars.

People lie for all different reasons, in all different sorts of contexts, but the one thing that I’ve observed common to (nearly) all liars is that, when they decided to tell the lie, they included in their calculation a determination that they won’t be caught. That assessment, that calculation, is shared by nearly everyone who’s ever told a lie in a legal setting. They think, essentially, “if I say this, they can’t prove otherwise.”

Not coincidentally, this is one of the most common ways that people get caught in a lie. They told the lie thinking that no one could prove otherwise, and it turns out they were wrong.

Boom. Thank you, Mr. or Mrs. Liar, you’ve just written my closing argument for me.

***

Now let’s turn to the news over the weekend that the Mueller team had acquired tens of thousands of emails of the Trump Transition Team, and more critically, had these emails in its possession when interviewing various Transition Team individuals.

If I am correct and the one element shared in common by most liars in deciding whether or not to lie is an assessment of whether they can be caught in their lie, and moreover, that documentary evidence is the best way to prove a lie to be a lie, what might we infer from Team Trump witnesses agreeing to speak to Mueller’s prosecutors without knowing that Mueller already had evidence in hand to disprove any lie that spilled from their mouths?

One thing we can reasonably infer is that Team Trump’s “can I get away with this lie” calculations were missing a critical data point. Whoops. This means that every provable lie they’ve told can, in fact, be proven a lie if it contradicts something different written in one of those emails. Also, they all might have been foolishly more inclined to lie, believing they were free to peddle whatever lie they chose to without consequence. Whoops again.

No wonder Team Trump is losing their sh*t over news of these emails (writing “no fair!” letters to Congress and such). More critically, it is quite likely transition officials chose to lie during their interviews thinking no one could prove otherwise, and it’s going to turn out they were wrong.