The materials in this chapter concern two procedural hurdles that defendants may confront at trial. We will first discuss presumptions, which are far less prevalent in criminal practice now than several decades ago. Our attention for the remainder of the chapter, and indeed of the book, will be almost exclusively on the place of “defenses” in the criminal law. These are unsettled areas of the law. The notion that defenses can be categorized as either excuse or justification, which is the primary topic in this chapter, is new to Anglo-Saxon jurisprudence. The distinction, however, is hardly academic; it has many practical, as well as theoretical, implications.
This chapter investigates what we mean when we say that D has a “defense.” Does a defense relate to an element of the crime? If so, how? May the state require the defendant to carry the burden of proof on a “defense”? And by what procedural mechanisms or labels may it do that? Chapters 16 and 17 investigate specific kinds of defensive claims. Chapter 16 looks at many claims that may be classified as “justifications,” while Chapter 17 considers claims of “excuse.” Throughout those two chapters, however, we will refer back to the issues raised in this chapter. They are all of the same cloth.