Exclusion of evidence
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If a particular item of evidence is inadmissible as a matter of law, then the judge has, in principle, no discretion to admit it. Of course, it is for the judge to determine how the law should be applied to questions of admissibility, so the judge does have some discretion, although it is indirect. You won't hear a judge say as a matter of law this evidence is inadmissible, but I want the jury to hear it anyway. Or, at least, if you do hear it, it will be in the report of an appeal case. To be sure, there are certain statutory provisions that allow a judge to admit evidence which, in general, would be inadmissible. One such example is s.114(1)(d) of the CJA_2003, which allows the judge to admit evidence which would normally be considered Hearsay. However, this does not give the judge a discretion to admit evidence in the face of the law -- this is a discretion granted by law.
So, in principle, if evidence is legally inadmissible, the judge cannot exercise a discretion to admit it. However, the converse is not true -- at common law judges have generally had a discretion to exclude evidence where the interests of justice so demand. These common law provisions are now reinforced by certain statutory measures.
The Police and criminal evidence act (1984) contains two major provisions to prevent the use of evidence that has been obtained unreasonably: s.76 and s.78. There is also a common law power to exclude. These provisions are summarised in the table below.
Section meta of evidence Reason for exclusion Burden of proof PACE s.76 Confession confession was made under oppression prosecution to prove beyond reasonable doubt. PACE s.78 Any evidence obtained unfairly defence to prove that the on the balance of probability common law Any evidence is more prejudicial than probative defence to prove that the on the balance of probability
s.76 applies in particular to confessions obtained in an oppressive way (see: Confession). Evidence so obtained should be excluded if it is unreliable. Naturally, actual or threatened violence would be classed as ooppression, but the section may apply to less outrageous behaviour. The usual practice is to define oppression as
the exercise of power in a burdensome, harsh, or wrongful mannger; unjust or cruel treatment.
This would class as oppression, for example, intimidating or bullying interview techniques. In addition, breaches of the Detention Code have led to confessions being exlcuded; for example, where a mentally handicapped person was interviewed outside the presence of a responsible person this was deemed to make the confession inadmissible.
To be excluded, evidence must not simply be obtained by opression, but the opression must be such as to make the evidence unreliable. Whether a court decides the evidence is unreliable depends on many factors. For example, where a man was threatened with continued detention if he did not confess to a drugs offence, his confession was held not to be excludable, as the court judged that as a repeated offender he should have been familiar with his rights and the interview procedure. Similar rulings have been made where the accused was denined access to legal representation (see below).
Moreover, even if the confession itself is excluded, it may still be possible to admit
- evidence that is obtained by following up information from the confession and,
- evidence that the accused speaks, writes or conducts himself in a particular way.
Section 78 applies to evidence which, all things being considered, has such an adverse effect of the fairness of the proceedings that it ought to be excluded. Reasons to invoke s.78 may include denial of access to legal advice, unwarranted detention, incorrect interview techinque (e.g., lack of formal caution, see: Cautioning before interview), abuse of compulsory powers to induce Self-incrimination and other breaches of the PACE codes.
As for s.76, the court must make a judgement on the particular facts of the case; however, unlike s.76 the onus is on the accused to prove that the evidence will adversely affect fairness.
PACE does not revoke the common law power of exclusion which, to some extent, overlaps with s.78. The general principle here is that evidence may be excluded if its prejudicial effect significantly outweighs is 'probative value'.