Observations on Cross-Examination and the Limits of Attacking Witness Credibility

As a current Master of International Law student, I have been delving into the intricacies of evidence law and, in particular, the rules that govern cross-examination. One area that stood out to me is the way the common law has historically handled questions going only to “credit” — that is, attempts to undermine a witness’s credibility rather than to address the substantive issues in the case.

The Basic Rule

The principle, set out by Chief Justice Latham in Piddington v Bennett & Wood Pty Ltd (1940) 63 CLR 533, is straightforward: any witness may be cross-examined in order to discredit them. However, if the questions relate solely to credibility and not to the matters directly in issue, the witness’s answers are generally final. Traditionally, opposing counsel cannot bring in additional evidence to contradict those answers — otherwise, trials would risk spiralling into endless disputes about side-issues.

Observations on Cross-Examination and the Limits of Attacking Witness Credibility

There are, of course, exceptions. The common law has allowed contradictions where:

• the witness is shown to be a “notorious liar”;

• there is evidence of corruption or improper motives;

• there are proven criminal convictions that the witness has denied; or

• there are inconsistent prior statements.

A statutory safeguard also applies: if the questioning imputes an uncharged crime, the witness may rely on the privilege against self-incrimination.

Principles of Proper Questioning

James Fitzjames Stephen, whose thinking influenced the Indian Evidence Act 1872, offered three guideposts — later endorsed by Lord Sankey — that remain useful:

1. Questions should only be permitted if the answers would seriously impair the credibility of the witness.

2. Questions are improper if they relate to matters too remote in time or trivial in character.

3. Questions are improper if there is a disproportion between the attack on character and the importance of the witness’s evidence.

4. 
   

These principles help prevent cross-examination from turning into character assassination, while still protecting the right to probe credibility.

Modern Judicial Approaches

Courts have applied these principles with varying levels of flexibility. In R v Richardson [1969] 1 QB 299, a witness was challenged with allegations ranging from hallucinations to perjury — an illustration of the wide latitude sometimes afforded. By contrast, in R v Edwards (1991) 2 All ER 266, the Court of Appeal limited questioning about police improprieties, allowing it only where adverse findings had been made in earlier proceedings.

Interestingly, there has been a gradual shift towards a more liberal approach in some cases. For example, the Court of Appeal overturned a conviction where the trial judge had refused to allow rebuttal evidence showing that a police witness may have threatened a defence witness. The appellate court held that credibility can, in certain contexts, be so central to the issues that strict adherence to the “collateral evidence” rule undermines justice.

My Reflections

What strikes me as a student is the tension between two competing values. On one hand, courts want to avoid collateral mini-trials over a witness’s entire life history. On the other, there is a deep commitment to fairness when the case turns on whether a witness should be believed.

The rules reflect centuries of trial practice trying to keep proceedings efficient and focused, but they also reveal a willingness to bend when justice demands it. In my view, this ongoing balancing act between efficiency, fairness to witnesses, and the rights of the accused underscores the living nature of evidence law.

It will be fascinating to see how courts continue to evolve this doctrine — especially in an era where credibility is increasingly challenged not only in the courtroom but in the public domain through digital records and online histories.