This chapter offers, from a comparative perspective, a consideration of possible approaches to defining the scope of the hearsay rule in criminal cases. In The Principles of Criminal Evidence (1989), Adrian Zuckerman called for a more flexible approach to criminal hearsay doctrine than that prevailing in England and Wales at the time. Some three decades later, the major common law jurisdictions retain rules that have the effect, broadly speaking, of presumptively excluding hearsay evidence in criminal cases. There has been considerable judicial and academic focus in recent times on issues associated with the exceptions to such exclusionary rules. This chapter examines a related question that, although fundamental, has attracted far less attention and remains relatively under-explored: what is, and what should be, the precise scope of the rules that presumptively exclude hearsay evidence in criminal cases? It is noted that the decision of the Supreme of Court of Canada in R v Baldree (2013) offers a radically different approach to this question from that taken in the Criminal Justice Act 2003 (England and Wales), the US Federal Rules of Evidence, the Australian uniform evidence legislation, or the Evidence Act 2006 (New Zealand). In the light of a consideration of the approaches taken in various jurisdictions and the implications of these approaches, the chapter concludes that the Canadian approach provides the most sensible basis for possible reform. Some suggestions on the way in which the relevant law in England and Wales might be reformed are also offered.