yes, evidence can be ineffective within the criminal trial process although it is mostly neccessary and effective. evidence can be regarded as an ineffective way of achieving justice if: the evidence is tampered with, the evidence is unlawfully attained. in other words, that is called "inadmissible evidence". evidence in the form of witness and expert testimony may be difficult to talk about, but it can also be falsified even under the oath. i'll give you a few cases:
- R v Woods 2012: evidence of an expert witness is usually considered valuable, however it can be failliable. Wood was convicted of the 1995 murder of girlfriend Caroline Byrne, and the evidence can from a testimony from an expert. However, this evidence was overturned because it was flawed due to being saturated with opinion rather than scientific proof, so it did not satisfy "beyond reasonable doubt".
- Darby v Director of Public Prosecutions 2004: sniffer dogs can only search for illegal drugs without a warrant at pubs, clubs, public transportation and large public events. Police have discovered methamphetamines unlawfully, so the evidence was inadmissable. However, this creates a dichotomy of whether it would be better if the evidence is very convicting and can easily solve a case, but it cannot be used because it was obtained unlawfully, or the protection of the right to privacy for the accused. This can be argued more into whether the criminal trial process protects the rights of offenders or focuses on punishing the offender.