What should happen when evidence is obtained unlawfully? The answer is crucial. It can result in a person being convicted or cleared, trust in criminal justice systems being undermined or strengthened, and human rights being respected or ignored. This report was developed for judges and prosecutors to assist in decision-making on illegally obtained evidence, based on four founding rationales:
- Reliability: Establishing the truth – whether and what criminal offence has been committed, who the perpetrator is and whether they bear criminal responsibility for their actions – is one of the main objectives of criminal proceedings.
- Deterrence: Courts should exclude illegally obtained evidence to discourage law enforcement officers from committing improprieties or illegal acts in the investigation of crime.
- Prevention: If a legal system sets certain standards for criminal investigations, people have corresponding rights. If those rights are violated, the suspect or accused person should not be placed at a disadvantage because of that violation and the evidence obtained through such violation should not be used against that person.
- Integrity: Criminal justice is based on public trust therefore justice must not simply be done but must be seen to be done. The public will lose faith in the administration of justice if judges condone wrongdoing by state authorities too easily and permit evidence obtained by deliberate, grave or systemic abuses of power to be used in criminal proceedings.
