This really can be a life-or-death question. Do jurors understand the instructions they receive before they go into deliberations? Probably not as well as you hope.

The British government released the results of a large study about the jury system. One minor finding was that only 31 percent of the research subjects were able to identify two questions the judge had directed them to answer. This was not a surprise to me, or to many people in the Forensic Linguistics community. Research in the United States has long produced similarly distressing results.

One particularly problematic instruction I have studied is the California instruction that tells the jurors how to decide whether a convicted murderer should be sentenced to death or to life imprisonment. (I presented a paper based on this instruction to the International Association of Forensic Linguists conference in 2009.) The root problem, as I see it, is that the committee that wrote the jury instructions was made up only of judges, law professors, and lawyers, that is, people in the legal profession.

Writing jury instructions is partly an exercise in technical writing, taking knowledge from specialists and making it accessible to people outside the field. The specialists, those on the committee now, are immersed in the language of the law, and they use words that lay people don’t know, or understand differently. Their professional training doesn’t include things like the most effective way to write for reader comprehension.

The core of this jury instruction is a list of eleven criteria the jurors must use to determine whether the death penalty is appropriate. (Life imprisonment is the default decision.) But this list is taken verbatim from the text of the statute: a document written by legislators to be read by lawyers. Research done by me and others has shown that the criteria are easily misunderstood. Having someone on the committee whose specialty is communication, rather than law, would help the cause of justice.

According to one study, this difficulty in comprehension is not limited to this one instruction, or even to jury instructions from California.

I have rewritten the instruction to increase comprehension, and the rewrite is available on my website. I’d be pleased to hear from anyone embarking on a project to write or rewrite jury instructions. Maybe I can help make them more comprehensible.

The British government report: