Over the past decade, criminal lawyers across Australia have begun encountering a term that was rarely used in courtroom forensic reporting only a few years earlier: activity level evaluation.
For many practitioners, the concept can feel new. In reality, it reflects a gradual evolution in forensic DNA interpretation that has been developing for more than two decades. What is new is not the science itself, but the increasing visibility of activity-level reasoning in criminal proceedings and forensic reports.
Understanding how and why activity-level reporting is emerging is becoming an important aspect of modern criminal DNA casework.
From Source Level to Activity Level
Historically, forensic DNA reporting in Australian courts has focused primarily on what is known as the source level. This involves determining whose DNA is present in a sample and, where possible, identifying the biological material from which that DNA may have originated.
Source-level findings can be highly probative in some contexts. However, they do not address how the DNA came to be present, when it was deposited, or whether it is connected to the alleged offending conduct. These questions sit at what forensic scientists describe as the activity level.
Activity-level evaluation considers the competing explanations for how DNA may have been transferred or persisted in a particular context. This includes assessing whether the findings are more consistent with one proposed sequence of events than another. Such evaluations are inherently complex and depend heavily on context, assumptions, and the available scientific data.
For many years, activity-level reasoning existed largely in the background of forensic interpretation. It was rarely expressed in formal reports and was seldom presented as a structured evaluative framework in Australian courts.
A Gradual Shift in Forensic Practice
Over the past two decades, a substantial body of international research has examined DNA transfer, persistence, and the interpretation of low-level and mixed DNA profiles. This research has increased scientific understanding of indirect transfer mechanisms and the limitations of source-level conclusions.
At the same time, there has been growing discussion within forensic science about the need to move beyond simply identifying DNA contributors and toward evaluating what the findings mean in the context of alleged activities. This has led to the development of structured approaches to activity-level evaluation in some jurisdictions.
In Australia, this shift is beginning to manifest in forensic reporting and testimony. Some laboratories and agencies have established or are developing formal activity-level reporting capabilities, while others are incorporating elements of activity-level reasoning into existing evaluative frameworks. As this practice evolves, criminal lawyers are increasingly likely to encounter activity-level opinions in the course of proceedings. The practical implications of DNA evidence that appears highly probative yet remains open to multiple interpretations are explored in our discussion of when DNA evidence appears stronger than it is in sexual assault cases.
When Activity-Level Issues Arise
Activity-level considerations may arise in a wide range of criminal matters, including sexual assault, serious assaults, and cases involving alleged contact with objects or environments. In many instances, DNA findings are capable of supporting multiple explanations. Determining which explanation is more plausible requires careful consideration of transfer pathways, persistence, and context.
Activity-level opinions may also emerge later in proceedings than initial source-level reports. In some matters, early forensic reporting may indicate that no DNA attributable to the accused has been detected, or that DNA findings are limited. At a later stage, further evaluative opinion may be sought or served addressing what those findings may imply about the alleged activity.
This can alter the perceived evidentiary landscape of a case, particularly where activity-level interpretation has not been considered at an early stage.
Why Early Consideration Matters
Activity-level evaluation does not arise in every case, and a formal activity-level report is not always required. However, where DNA evidence features prominently, early consideration of how activity-level issues may be framed can assist in avoiding later surprises and in ensuring that the forensic significance of the findings is properly understood.
Independent forensic review can assist in identifying whether activity-level interpretation is likely to become relevant, whether the available scientific data can support such evaluation, and how the DNA evidence may ultimately be presented at trial. This is particularly relevant in sexual assault matters, where DNA findings may appear corroborative without resolving how the material was deposited. This is particularly important where DNA findings appear limited or neutral at source level but may be interpreted more broadly in context.
Conclusion
Activity-level reporting is not a new science, but its increasing visibility in Australian criminal proceedings reflects a broader shift in forensic interpretation. As DNA technology becomes more sensitive and forensic evaluation more sophisticated, the distinction between identifying DNA and interpreting its significance is becoming more pronounced.
For criminal lawyers, understanding when activity-level issues may arise – and what they can and cannot resolve – is now an important part of assessing DNA evidence in modern casework.
Helen Roebuck is an independent forensic DNA expert who provides specialist assistance to criminal lawyers in matters involving complex DNA evidence. Her work includes evaluation of source-level findings, transfer and persistence considerations, and the interpretation of DNA evidence within the context of alleged activities.
Where DNA evidence is central to a matter, early independent review can assist in clarifying whether activity-level issues are likely to arise and how the forensic evidence may ultimately be interpreted in court.