Interrogations-and-Confessions-Handbook

Why do Suspects Confess? Empirical Findings 131
McKenzie, 1989; McConville, 1993; Moston, Stephenson & Williamson, 1992;
Softley, 1980), even though in such cases the confession may add little to the
overall strength of the case. When the evidence against suspects is weak, then a
confession may be the main evidence used at trial to convict them. In addition,
when a confession is forthcoming, the post-admission statement (i.e. the details
of the criminal act as provided by the suspect once he begins to confess) can
be used to test out the validity of the confession and may provide important
corroborative evidence. Does the suspect possess ‘special knowledge’ that was
not in the public domain? The strongest corroboration is when the confession
leads to the discovery of further incriminating evidence which was previously
unknown to the police (e.g. discovery of the murder weapon, the victim’s body,
recovery of stolen goods). The extent to which the police attempt to corroborate
pieces of information contained in the confession varies considerably. Inbau
et al. (2001) strongly recommend that the validity of the confession be carefully
investigated; their concern is about the large number of defendants who
retract their confession and the risk of acquittal at trial without corroborative
evidence. Obtaining a confession should not be seen as a substitute for a thorough
criminal investigation. Indeed, McConville (1993) has noted a trend in
England towards the acquisition of evidence independent of a confession. This
is due to improved post-arrest investigative work.
The importance of confession evidence was recognized by the Royal Commission
on Criminal Justice:
Where a suspect has made a confession, whether at the moment of arrest, on the
way to the police station, in the presence of the custody officer, or at a tape-recorded
interview at the police station, it must normally constitute a persuasive indication
of guilt, and it must in principle be desirable that, if a not guilty plea is entered
in spite of it, the jury are given the opportunity of assessing its probative value
for themselves. On the other hand, confessions which are later found to be false
have led or contributed to serious miscarriage of justice (Royal Commission on
Criminal Justice Report, 1993, p. 57).
What the Commission may not have fully appreciated is the potentially damaging
impact that confession evidence can have on a jury. Kassin and Neumann
(1997) have produced experimental evidence to show that confession evidence
has a stronger impact on juror’s decision making than any other type of probative
evidence, including eyewitness and character evidence. This finding is
very important. It helps to explain why confession evidence is found to be so
common in cases of wrongful convictions.
One might expect that where there is a legal corroboration requirement, as
in the United States of America and Scotland, detectives would be motivated
to seek evidence to support the validity of the confession. According to Ayling
(1984), this does not always appear to be the case. In other words,
Contrary to the assumptions behind the corroboration rule, the rule does not
motivate police to gather independent evidence (p. 1193).
Studies that have attempted to assess the importance of confession evidence as
a part of the prosecution case are scarce. Inbau et al. (2001) make it clear that