Towards cumulative forensic science: a commentary on ‘Methodological problems in every black-box study of forensic firearm comparisons’

Cuellar et al. recently found that methodological flaws in black-box studies of forensic firearms analysis mean that validity cannot be determined from those studies. Their paper can also be read to indicate that the presence of some of these flaws means that the associated study is so unsound that it can only be used to plan future properly designed validation studies. We seek to clarify that each of the identified flaws, taken individually, does not necessarily prevent studies from contributing to a strong, cumulative research basis for forensic practices. That said, we agree that the overall body of research must avoid the flaws identified by Cuellar et al., and, based on their analysis, it appears the overall body of research has not avoided these flaws. We go on to suggest practices that can help ensure forensic science studies can efficiently and safely build on each other.