Final answer:
The greatest weakness of class evidence is its inability to uniquely identify a single source, making it less impactful and conclusive in a criminal investigation compared to individualized evidence.
Step-by-step explanation:
The greatest weakness of class evidence is that it does not uniquely identify a single source but can apply to a large population. This inherent limitation means that while class evidence can place an individual within a larger group, it cannot specifically differentiate between individuals within that group. This raises two significant factors that contribute to its weakness: First, class evidence can support the presence of an individual at a crime scene but falls short in its ability to conclusively link an individual to the exclusive commission of a crime.
Second, the widespread applicability of class evidence reduces its impact in the eyes of a jury as compared to individualized evidence, which can provide a direct link to a singular individual. In forensic analysis, relying on class evidence alone can therefore be far less conclusive and persuasive than individualized evidence, which is typically necessary for definitive assertions in a criminal investigation.