Introduction

Factual Impossibility in Attempt

Introduction

Most attempts that fail do so because something gets in the way of the plan: a police officer arrives, the victim escapes, or the defendant loses nerve and stops. Impossibility cases present a different kind of failure, because nothing interrupts anyone. The defendant performs every act he set out to perform, and the crime still cannot occur because some fact about the world differs from what he believed. A defendant in that position has an intuitive argument available, as two short scenes show.

The common-law answer is that the argument fails. A defendant charged with attempt may not defend by showing that he could not complete the substantive offense, meaning the finished crime the attempt was aimed at, because of a physical or factual condition he did not know about.¹ The rule also reaches mistakes about attendant circumstances, which are the surrounding facts that an offense definition makes relevant, such as the character of the property taken or the identity of the person targeted. Whenever the conduct would have been a crime had those circumstances been as the defendant believed, the mistake gives him no defense.² The rule takes this shape because attempt punishes a defendant for what he intended and for what he did to carry that intention out. The empty pocket and the empty chamber reveal nothing about either. The thief who reached into the pocket was as determined, and as dangerous, as one who found a wallet there, and the difference between them is a fact that neither knew or controlled. A defense built on such a fact would sort defendants by luck while leaving their purposes and their conduct identical.

The rule has a boundary, and this chapter teaches both the rule and the line that marks it. A defendant who is mistaken about the law rather than about the facts, believing his conduct is criminal when the law does not forbid it, presents true legal impossibility, and that form of impossibility still defeats a charge of attempt.³ Because the two kinds of mistake can look alike on a first reading of the facts, the chapter first fixes what an impossibility claim is, then teaches the common-law rule and its exception, and finally gives a method for sorting any set of facts onto one side or the other. The starting point is the definition of an impossibility claim and the way it differs from an attempt that was merely interrupted.