The collateral evidence rule
| Author | Adrian Keane |
| DOI | 10.1177/1365712714568623 |
| Published date | 01 April 2015 |
| Date | 01 April 2015 |
| Subject Matter | Articles |
Article
The collateral evidence rule:
A sad forensic fable involving
a circus, its sideshow,
confusion, vanishing tricks
and alchemy
Adrian Keane
City University, London, UK
Abstract
The collateral evidence rule restricts the admissibility of evidence that undermines the credit of
witnesses. Given the obvious importance of such evidence to accurate fact-determination, it is
remarkable that the rule has been subject to so little academic scrutiny. This article, a critical
analysis of the rule, argues for its abolition. In doing so, regard is had to other rules that impinge
on its ambit and to the way in which it has been applied and modified in a number of jurisdictions.
Keywords
evidence undermining credit of witnesses, collateral evidence rule, critical analysis of, case for
its abolition
Introduction
The collateral evidence rule is complex and of uncertain scope; it seems that some types of evidence
have been improperly included in the list of exceptions to the rule and other types of evidence improperly
excluded from it. Historic and contemporary criticism of the rule has mainly focused on the difficulty in
drawing the distinction, which application of the rule requires, between matters going merely to credit
and matters going to the issue. It has been suggested that the distinction is becoming obsolescent and in
some cases is reduced to vanishing point. In this article it will be argued that the distinction between
credit and issue is nowhere near obsolescent, never vanishes and should continue to be drawn as a part
of a rational fact-finding process. It will also be argued, however, that the collateral evidence rule should
be repealed without replacement. There are four powerful reasons for such a conclusion. First, operation
of the rule can mislead the tribunal of fact, unfairly skew decision-making and lead to injustice. Sec-
ondly, a rule-and-exceptions approach is not appropriate. Thirdly, the rule, as cast, does not achieve its
aim. Fourthly, the rule is simply unnecessary: its scope has been severely curtailed by statutory
Corresponding author:
Adrian Keane, City University, London EC1V 0HB, UK.
Email: A.N.Keane@city.ac.uk
The International Journalof
Evidence & Proof
2015, Vol. 19(2) 100–119
ªThe Author(s) 2015
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DOI: 10.1177/1365712714568623
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restrictions, especially those relating to the bad character of witnesses; and its purpose, where it does
apply, can be achieved by the continued application of well-established common law principles relating
to cross-examination coupled with a more robust approach to the exclusion of evidence on the basis of
such trial management factors as delay, expense and confusion.
The rule
The collateral evidence rule applies in both civil and criminal proceedings. It is long-standing; it had
become well-established by the early 19th century. The rule, in its modern form, derives from Harris
vTippet.
1
A defence witness denied that he had attempted to dissuade a witness for the plaintiff from
attending the trial. It was held that evidence contradicting the denial was inadmissible; ‘such collateral
inquiries would lead to endless confusion’. Although the rule is often cast in terms of evidence in rebuttal
of a ‘denial’, there seems to be no good reason, in principle, why it should not also apply in the case of a
non-admission, as when the witness prevaricates or says that she does not recall.
2
A good description of the rule was furnished by Scrutton LJ in Hobbs vTinling:
3
When a witness has given evidence material to the issues in the case you can cross-examine him on matters
not directly material to the case in order to ask the jury to infer from his answers that he is not worthy of belief,
not a credible person and therefore that they should not accept his answers on questions material to the case as
true. This is cross-examination as to his credibility, commonly called cross-examination to credit. But as it is
on matters not directly material to the case, the party cross-examining is not allowed to call evidence-in-chief
to contradict his answers.
The phrase ‘matters not directly material to the case’ has been taken to mean matters that are not relevant
to the facts in issue in the case. On one view, the rule applies not only to answers given in cross-
examination, but also to answers given in examination-in-chief.
4
Under the rule, answers on collateral matters must be treated as final. Finality for these purposes
means not that the fact-finder is obliged to accept the truth of the answers, but simply that the cross-
examining party is not allowed to call contradictory evidence. Nor should that party suggest to the
witness that he is in a position to call such evidence.
5
The celebrated test as to whether a matter is collateral is that of Pollock CB in A-G vHitchcock:
6
The test whether a matter is collateral or not is this: if the answer of a witness is a matter which you would be
allowed on your own part to be proved in evidence—if it have such a connection with the issues, that you
would be allowed to give it in evidence—then it is a matter on which you may contradict him.
It has been said frequently that the test seems to be circular:
7
‘you may contradict on matters on which
you may contradict’
8
or ‘a matter is in issue if it is in issue’.
9
However, the test is now generally accepted
1. (1811) 2 Camp 637.
2. The Evidence Act, s. 106, for Australian jurisdictions where the Uniform Evidence Acts apply, was expressly amended to cover
failure to admit or agree: see Australian Law Reform Commission (2005: 412–414).
3. [1929] 2 KB 1 at 18–19.
4. See Pacioccoand Stuesser (2011: 349). But presumablythe cross-examining partyis not deprived of the right to cross-examineon
the collateral mat ter. In RvS[1992] CrimLR 307, bizarrely, the very fact that the defencehad elicited in cross-examinationthe
evidence that they wished to rebut was includedamong the reasons for not allowing evidence inrebuttal.
5. SvDamalis 1984 (2) SA 105.
6. (1847) 1 Exch 91 at 99.
7. See e.g. per Henry J in RvFunderburk [1990] 1 WLR 587 at 598: ‘If a fact is not collateral then clearly you can call evidence to
contradict it, but the so-called test is silent on how you decide whether that fact is collateral’.
8. Newark (1992: 170).
9. Seabrooke (1999: 389).
Keane 101
101
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