Why is the conviction rate not a reliable measure of a fire investigation unit's effectiveness?

The conviction rate is not a reliable measure of a fire investigation unit's effectiveness primarily because it is influenced by external factors such as the behavior and decisions of prosecutors. Fire investigation units may perform their work competently and gather substantial evidence, but the final decision to prosecute, the way cases are presented in court, and the legal strategies employed can significantly affect the outcome of cases. If a prosecutor decides not to pursue a case vigorously or if the evidence is deemed insufficient for prosecution, the unit may receive criticism even if their investigative work was sound.

While it is true that variations in case types and annual fluctuations can affect perception, the overarching influence of prosecutorial decisions makes conviction rates less about the fire investigation unit's performance and more about the legal system’s complexities and challenges. This connection underscores the need to evaluate fire investigation effectiveness through metrics that reflect the quality of investigations rather than judicial outcomes.