The readability of expert reports for non-scientist report-users: reports of DNA analysis

DNA evidence can be extremely compelling. With ongoing scientific advances and applications of DNA evidence in the criminal justice system, it is increasingly important that police, lawyers, and judges recognise both the limitations of DNA evidence and the strength of the evidence in particular cases. Because most forensic sciences are formally communicated via expert reports, we analysed the readability of 68 such reports of DNA evidence from 6 of 8 Australian jurisdictions. We conducted content analyses using three categories: content and sequence, language, and format. Categories contained qualitative and quantitative items drawn from theory and past research. Report styles differed by jurisdiction and by main audience - police and the courts. Reports for police were brief and few links were made between sections in these reports. Reports for courts were less brief and used either legal or scientific styles. Common sections in reports for courts included: the scientist's specialised knowledge; laboratory accreditation information; item list; results; and notes on interpretation. Sections were often not in a logical sequence, due to the use of appendices. According to Flesch Reading Ease scores, reports for police had language that was fairly difficult, and reports for courts, difficult. Difficulty was compounded by the use of specialist terms. Reports for police and the appendices of reports for court often used very small font and single line spacing. Many reports for court contained tables that spanned several pages. Suggestions based on theory and past research are provided to assist scientists to enhance the readability of reports for non-scientists.