When they retired to consider their verdict in the high profile cricketer Ben Stokes affray trial, the judge helpfully provided a “route to verdict” document to the jury.
This kind of document can be drawn as a simple decision tree. It clearly outlines the questions the jury needed to answer and the order they should consider them in. Each yes / no / maybe decision leads to the next question or verdict.
It’s a good demonstration of how a decision tree approach can cut through large amounts of potentially confusing data to identify the options and get to the core of what needs to be decided.
Here is the tree outline and the gist of the questions:
Q 1 Did (the defendants) use or threaten violence towards another person?
Yes = Q 2a No, or he may not have done = Not guilty
Q 2a Did they genuinely believe that it was necessary to use or threaten that violence so as to defend himself and/or another?
Yes = Q 2b No = Q 3
Q 2b Was the force he used or threatened “reasonable” in the circumstances as he perceived them to be?
No = Q 3 Yes / maybe = Not guilty
Q 3 Was the conduct such as would cause a person of reasonable firmness present at the scene to fear for his personal safety?
Yes = Guilty No / may not have = Not Guilty
The logic of the law lends itself to a decision tree type process of decision making. Where logic is expected to lead to a decision, drawing out the options to consider in a decision tree diagram can be helpfully clarifying.
Ben Stokes was acquitted of affray by the jury following a week-long trial at Bristol Crown Court in August 2018.
More about decision trees