This chapter argues that relevant evidence must be excluded on the ground of public policy on certain conditions. It explores two of these conditions: when the evidence concerns certain matters of public interest considered to be more important than the full disclosure of facts to the court, and when it relates to miscellaneous matters connected with litigation. The chapter also discusses evidence that has been illegally obtained, though this topic is not usually covered under the umbrella of public policy. Although there is no comparably strict general exclusionary rule, it is increasingly the case that the courts recognize the existence of an exclusionary discretion. This is governed in part by weighing the public interest in the conviction of guilty criminals against the public interest in the preservation of basic civil liberties.
Chapter
X. Public policy
Chapter
14. Hearsay admissible at common law
This chapter considers the following categories of hearsay: statements in public documents, works of reference, evidence of birth, age, and death, evidence of reputation, statements forming part of the res gestae, and statements which are admissions made by an agent of a defendant. All of these categories were established at common law as exceptions to the rule against hearsay, and all of them have been preserved by statute. The categories relating to age and res gestae have been preserved in criminal but not civil proceedings. All of the other categories have been preserved in both criminal and civil proceedings.
Chapter
14. Hearsay admissible at common law
This chapter considers the following categories of hearsay: statements in public documents; works of reference; evidence of birth, age, and death; evidence of reputation; statements forming part of the res gestae; and statements which are admissions made by an agent of a defendant. All of these categories were established at common law as exceptions to the rule against hearsay, and all of them have been preserved by statute. The categories relating to age and res gestae have been preserved in criminal but not civil proceedings. All of the other categories have been preserved in both criminal and civil proceedings.
Chapter
20. Experts and opinion evidence
This chapter discusses the law on experts and opinion evidence. As a general rule, opinion evidence is inadmissible: a witness may only speak of facts that he personally perceived, not of inferences drawn from those facts. However, there are two exceptions to this general rule: (i) an appropriately qualified expert may state his opinion on a matter calling for the expertise that he possesses; and (ii) a non-expert witness may state his opinion on a matter not calling for any particular expertise as a way of conveying the facts that he personally perceived. Experts may also give evidence of fact based on their expertise. The chapter covers the duties of experts and the rules which apply where parties propose to call expert evidence.
Chapter
21. Public policy
The public interest in efficient and fair trials may be seen as underlying the rules of disclosure in civil litigation, whereby a litigant is obliged to make pre-trial disclosure of the documents on which he relies and the documents that adversely affect his own case or adversely affect, or support, another party’s case, even though such documents may not be admissible evidence at the trial. There is also a public interest in enabling material to be withheld where its production would harm the nation or the public service. Where these two kinds of public interest clash and the latter prevails over the former, relevant and otherwise admissible evidence is excluded at trial. Such material is said to be withheld by reason of ‘public interest immunity’. This chapter discusses the development of the modern law on public interest immunity; the scope of exclusion on grounds of public policy; and related procedural issues in civil and criminal cases.
Chapter
20. Experts and opinion evidence
This chapter discusses the law on experts and opinion evidence. As a general rule, opinion evidence is inadmissible: a witness may only speak of facts that he personally perceived, not of inferences drawn from those facts. However, there are two exceptions to this general rule: (i) an appropriately qualified expert may state his opinion on a matter calling for the expertise that he possesses; and (ii) a non-expert witness may state his opinion on a matter not calling for any particular expertise as a way of conveying the facts that he personally perceived. Experts may also give evidence of fact based on their expertise. The chapter covers the duties of experts and the rules which apply where parties propose to call expert evidence.
Chapter
21. Public policy
The public interest in efficient and fair trials may be seen as underlying the rules of disclosure in civil litigation, whereby a litigant is obliged to make pre-trial disclosure of the documents on which he relies and the documents that adversely affect his own case or adversely affect, or support, another party’s case, even though such documents may not be admissible evidence at the trial. There is also a public interest in enabling material to be withheld where its production would harm the nation or the public service. Where these two kinds of public interest clash and the latter prevails over the former, relevant and otherwise admissible evidence is excluded at trial. Such material is said to be withheld by reason of ‘public interest immunity’. This chapter discusses the development of the modern law on public interest immunity; the scope of exclusion on grounds of public policy; and related procedural issues in civil and criminal cases.
Chapter
10. Public interest immunity
This chapter first explains exclusion of evidence on the grounds of the public interest immunity (PII) doctrine in relation to the public interest in non-disclosure of documents. The chapter examines areas of public interest that are covered by possible PII claims. These include national security, defence and foreign policy, protection of children, the identity of police informers, and confidential records held by public bodies. The difference between PII and closed material procedures (CMPs) is outlined. The chapter, concentrating on civil cases, lists the landmarks in the evolution of the common law doctrine. It considers the extent which it has been influenced by the Strasbourg jurisprudence. Attention is given to the role of national security matters in the evolution of the law.
