THE COLLATERAL FACTS BAR

A DEFENCE OF THE CATEGORICAL APPROACH

Abstract

The collateral facts bar excludes evidence that contradicts a witness on collateral factual matters, in order to save time and avoid confusion of issues. A collateral matter is often said to be one that relates to the credibility of the witness. Stated in this form, the rule against proof of collateral facts is difficult to apply because many matters which relate to the credibility of a witness seem to be proper matters for independent proof. So, some commentators and courts have proposed a principled approach, according to which contradicting evidence would not be categorized as collateral or not but would be admitted or excluded based on a case-by-case assessment of the advantages and disadvantages of hearing it. But if the categorical approach is stated properly, to exclude contradicting evidence as collateral when its only function in the trial is to impeach the witness’s credibility and to admit it otherwise, a principled approach becomes unnecessary. Moreover, a principled approach to collateral facts may create the mischief the collateral facts bar is supposed to avoid. The categorical approach has all the resources it needs to distinguish between admissible and inadmissible contradicting evidence.