Decision tree as guide to jury in reaching verdict

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:

route to verdict drawn as a decision tree

     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.

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