Cromwell’s Rule: A Lawyer’s Guide

London 1661—One of the more curious episodes of British history involves the postmortem execution of British statesman and military dictator Oliver Cromwell. After a lifetime of political and military intrigue, Cromwell (1599 – 1658) died of natural causes while serving as Lord Protectorate, which, for all practical purposes, meant he was Britain's head of state. Through questionable means, Cromwell helped engineer the Commonwealth, a republican form of government, following a series of wars and conflicts between England, Wales, Scotland, and Ireland. 

Something curious happened a little over two years after Cromwell’s death: Charles II, Cromwell’s adversary, returned to England and became the king of a “united” England, Scotland, and Ireland. At some point, to purge deeds of the past, Charles ordered Cromwell’s body exhumed and executed. You read that right: Cromwell’s body was dug up and hanged, and his head was placed on a pole atop Westminster Hall for more than 20 years.

And we think we live in dramatic times.

This fascinating and bizarre episode aside, Cromwell may be better remembered for something he wrote to the Scottish General Assembly on the eve of a crucial battle: “I beseech you, in the bowels of Christ, think it possible that you may be mistaken.” Centuries later, statistician and author Dennis Lindley coined this interesting phrase “Cromwell’s Rule,” with a straightforward interpretation: Beware of absolute certainty. There is no such thing.

Looking at the Probabilities

Cromwell’s Rule has some significance in the field of Bayesian statistics, which has been defined as “an approach to data analysis based on Bayes’ theorem, where available knowledge about parameters in a statistical model is updated with the information in observed data.” Simply stated, when making statistical models, one needs to look at what the past data says and ask what that prior information may indicate.

That, in turn, helps form the basis of what may happen in the future. The problem (not only in statistical analysis, but also in any decision-making setting) is when individuals revert to absolute positions when making evaluations or decisions and ignore prior data that may indicate alternative conclusions—i.e., there's a 0% chance of an event occurring.

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Human beings—even lawyers—tend to gravitate toward certainty, or, at the very least, to search for certainty. Lack of certainty is arguably the most significant driver of human anxiety—from who is going to win the Super Bowl, to the outcome of an election, to our next doctor’s appointment. We fill the void with our internal default positions in the face of uncertainty. With litigation, that can take the form of certain pronouncements about the outcome of a particular case: “There’s no chance the judge will let in this piece of evidence; the jury will never find my client liable; there’s no way the other side can claim privilege for that document; a verdict will never reach that limit.” And that's just the positive side of things.

Confirmation Bias

The challenge for litigators and claims professionals is fighting against our internal cognitive biases. This is best done in two parts: recognizing when we are doing it and developing the skills to overcome it.

Let’s examine a type of cognitive tendency we are all acquainted with: confirmation bias. When we have a hypothesis or conclusion, we tend to elevate the information supporting that conclusion and disregard the rest. In his book, “Misbelief – What Makes Rational People Believe Irrational Things,” psychologist and behavioral economics professor Dan Ariely writes, “When we are motivated in one direction or another, confirmation bias kicks in and leads us to seek information that fills that need, regardless of its accuracy. And then the story gets more complex: We construct narratives to get to the conclusions we want to get to…it’s how we think about our thinking gets us into trouble as we part ways with reality.”

Think about this in the classic personal injury context. Take your aggressive plaintiffs’ attorney, who advertises almost entirely on the basis of fighting crooked insurance companies: Every claim’s examiner is a hack, and every defense expert is a hired gun. The defense, however, cannot claim moral superiority. How often have we asserted (even silently, to ourselves) that the plaintiffs are exaggerating, or that their attorneys are billboard-hugging ambulance chasers? The narratives we write in our heads drive (often subconsciously) how we litigate. How we think about things becomes our reality, whether or not the evidence supports it.

Do we then account for the possibility that our narratives are wrong? Probably. Any worthwhile defense professional not living under a rock will likely acknowledge the fraught litigation environment we are living through. But does the bias go deeper, invading the very foundations of our case evaluations? We all know it is wise to roundtable a case with our coworkers and colleagues before going to mediation, and certainly before trial. But are we thoroughly interrogating each vital position—liability, witness credibility, reliance of experts, admissibility of supporting evidence, verdict ranges?

Returning to another tenant of psychology, lawyers would do well to remember the Dunning-Kruger effect, another interesting concept that “occurs when a person’s lack of knowledge and skill in a certain area causes them to overestimate their own competence.” I can’t think of a profession more vulnerable to this concept than ours, where our jobs (quite literally) require us to become mini-experts on whatever subject matter we’re litigating over—from construction practices to orthopedic surgery to normal perception/reaction times in automotive braking. We are vulnerable to these evolutionary tricks of the mind, and we, as professionals, must guard against them. These tricks affect the way we litigate and try cases.

Do We Really Have Things Locked Up?

Do not despair—this is neither an invitation for indecision nor an encouragement to chase your ideas down a rabbit hole. As any litigation professional knows, sometimes a bad decision is preferable to no decision. But both things can be true at the same time. You can thoroughly interrogate your own decision-making process and consider whether you are “mistaken” without perseverating indefinitely. Here are some well-worn and obvious practices that we can utilize to help build resilience against confirmation bias while, at the same time, sharpening our rational analysis:

Pre-Mediation Case Evaluations: Before you ever send a settlement evaluation to a client, be sure to share that evaluation with trusted coworkers, family, or friends. Case evaluations should not be made in a vacuum. An opportunity to listen to lawyers and non-lawyers alike gives you the range of perspectives necessary to guard against bias and groupthink. Of course, you always need to be mindful of your ethical considerations and attorney-client confidences. Naturally, the most significant latitude for sharing information exists with coworkers, where you can freely share case information and subject your positions to rigorous inquiry. To the extent you can seek alternative views in addition to your own, do so because you can (ideally) excise biases before they spread and infect the far reaches of your cases.

Mock Juries: Mock juries are incredibly insightful in suitable high-value or potential Nuclear Verdict cases. But beware: they are not a predictive tool of what will happen at trial. Think of it like political polling with better accuracy. Mock juries provide you with a snapshot of where your case stands on that day and possible outcomes for how your evidence and arguments will be interpreted. People understand and express things differently, bringing their own biases, life experiences, and perceptions of case values and verdict ranges. Having the intellectual humility to open yourself up to this process will only strengthen your case and expose you and your client to issues you must consider.

Jury Verdict Research: While data isn’t everything, it is an important piece of the puzzle of understanding the limits of exposure. Anecdotal and outdated results aren't irrelevant, but consider them with caution. Just because you settled that L-4 / L-5 bulging disc case in 2013 for $98,000 doesn't mean you can do it again a dozen years later. Conducting jury verdict research is an appropriate way to take the pulse of how juries in your venue are deciding similar cases. Naturally, the results will work one way or another for settlement and mediation purposes.

Don’t Run From The Bad Facts And Witnesses: Watch how hard you're trying to explain away facts and testimony that negatively reflect on your client. To some extent, all defense work involves explaining away bad or unhelpful facts. But blind allegiance to your narrative can lead to disastrous consequences. While you want the jury to believe your client's story, you shouldn't be so gullible. Embrace the reality that a jury may hear this evidence and posture your case evaluations with these possibilities in mind.

Don’t Overlook Spoliation Issues: Spoliation occurs when potential pieces of evidence are not preserved or are discarded prior to and during litigation. This includes everything from a piece of paper to an email exchange to a piece of equipment. These issues can be very complicated and drastically affect a case’s value. Never assume that you can rationally explain to a judge or jury how a piece of evidence, particularly vital, has been spoliated. Or that it is unimportant. Even when the facts are in your favor, the extent to which a plaintiff's attorney can argue your client spoliated evidence and, by logical extension, violated its own policies and procedures, juries will be listening.

No one knows yet the full extent of how the legal profession will change with the widespread use and evolution of artificial intelligence. What we do know, however, is the human mind's ability to deceive itself. Biases are real, and they are part of being human. The trick is not to rid yourself of them because that is a fool’s errand. The trick is being mindful of them and using the appropriate steps to make sure you're getting them to work for your client and not against you. You don’t want future lawyers digging up your bones just to make a point.