Admissibility of Improperly Obtained Physical Evidence in the Scottish Criminal Trial: the Search for Principle

Exclusion of evidence in times of mass surveillance. In search of a principled approach to exclusion of illegally obtained evidence in criminal cases in the European Union

“…Secondly, according to the disciplinary principle, evidence would need to be excluded only if it was gathered illegally by a state official. If the argument underpinning the principle is that exclusion is required to deter and punish law enforcement officers, exclusion would be pointless if the illegality had been committed by a private citizen (Duff, 2004: 162).…”

“…Precisely in cases in which law enforcement officers have deliberately violated procedural rules, there is more reason to exclude the resulting evidence in an attempt to deter them from flouting the law in the future, compared to where the breach is a result of mere ignorance or a mistake (Mirfield, 1997: 31). While emphasis on the law enforcement officer's motives is consistent with only endorsing the disciplinary principle, it becomes less defensible if also the protection of the suspect is considered a relevant factor in deciding on admission of illegally obtained evidence, as will be argued below (Duff, 2004: 161). Secondly, according to the disciplinary principle, evidence would need to be excluded only if it was gathered illegally by a state official.…”

“…If courts would be allowed to pick and choose which factors they take into account and what weight they attach to them in the exercise of their discretion, this may lead to arbitrary and inconsistent decision making (Re, 2014: 1904). Duff argues in response that the guiding criterion for courts should be that of the moral legitimacy of the admission of evidence (Duff, 2004: 173), but it is questionable whether this criterion is sufficiently clear and precise to ensure consistent case law. It seems proponents of the principle would counter this criticism by re-emphasising the strengths of the principle.…”

“…According to the reliability principle determining the truth of the criminal charges is the sole purpose of the criminal trial, and evidence should be admitted or excluded only based on its reliability (Ashworth, 1977: 723; Duff, 2004: 152, 154–155). Bentham (1825: 2–3) is often cited as arguing that the rectitude or accuracy of the decision is paramount in the law of evidence.…”

“…The deterrence or disciplinary principle 43 posits that courts should exclude illegally obtained evidence in order to discourage law enforcement officers (police, prosecutors, investigating judges) from committing improprieties and illicit acts in the investigation of crime and thus protect citizens’ civil liberties (Duff, 2004: 160–161; Zuckerman, 1989: 349). The idea is that, if judges routinely exclude improperly obtained evidence, this sends a message to state officials that there is nothing to be gained from breaking the law and consequently they will refrain from doing so (Roberts and Zuckerman, 2010: 151).…”