justification is built into the very concept of negligence; but it is not part of the concept of knowingly or intentionally harming another In principle, one could break down the analysis of unjustifiable risk creation into two issues(1)the significance of the risk created; and(2)the justifiability of creating that risk(which we might also characterize as the burden of taking a precaution against that risk). The law could then explicitly develop a range of standards: creating a trivial risk of a trivial harm requires only a slight justification; creating a more significant risk of a trivial harm requires a more weighty justification; creating a significant risk of a more significant harm requires an even more weighty justification; and so forth. But the tort conception of negligence instead ordinarily employs a single standard, with a sliding scale: the justification for imposing a risk must ordinarily be weightier as the probability and severity of the harm risked increases. Only when the significance of the risk reaches a relatively high level, and the actor is aware of a relatively high level of risk or intends to cause harm, does the"sliding-scale negligence test give way to the qualitatively different standards for reckless and intentional torts Ill. The modern criminal law conception of negligence: unreasonable inadvertence and unreasonable mistake Although the standard tort conception understands negligence as unreasonably unsafe conduct, modern criminal law emphasizes a different cognitive conception of negligence--namely, the actors unreasonable inadvertence or unreasonable mistake. Criminal law employs other conceptions of negligence as well, but it will prove useful to characterize this cognitive conception as the"modern criminal law conception before introducing further complexity See Simons, Negligence, supra note 1=, at 56-57; Dan Dobbs, The Law of Torts sS26 See Draft Restatement (Third) of Torts, supra note 2=, s$1, 2 I describe this as the "modern"criminal law conception because the influential Model nal criminal law doctrine, by contrast, does not employ or emphasize any single conception of negligence. Instead, it contains a variety of doctrines that could be broadly classified as involving negligence-including Simons, Dimensions of Negligence 8/7/02justification is built into the very concept of negligence; but it is not part of the concept of knowingly or intentionally harming another. In principle, one could break down the analysis of unjustifiable risk￾creation into two issues—(1) the significance of the risk created; and (2) the justifiability of creating that risk (which we might also characterize as the burden of taking a precaution against that risk). The law could then explicitly develop a range of standards: creating a trivial risk of a trivial harm requires only a slight justification; creating a more significant risk of a trivial harm requires a more weighty justification; creating a significant risk of a more significant harm requires an even more weighty justification; and so forth. But the tort conception of negligence instead ordinarily employs a single standard, with a sliding scale: the justification for imposing a risk must ordinarily be weightier as the probability and severity of the harm risked increases.5 Only when the significance of the risk reaches a relatively high level, and the actor is aware of a relatively high level of risk or intends to cause harm, does the “sliding-scale” negligence test give way to the qualitatively different standards for reckless and intentional torts.6 III. The modern criminal law conception of negligence: unreasonable inadvertence and unreasonable mistake Although the standard tort conception understands negligence as unreasonably unsafe conduct, modern criminal law emphasizes a different, cognitive conception of negligence—namely, the actor’s unreasonable inadvertence or unreasonable mistake. Criminal law employs other conceptions of negligence as well, but it will prove useful to characterize this cognitive conception as “the” modern criminal law conception before introducing further complexity. 7 5 See Simons, Negligence, supra note 1=, at 56-57; Dan Dobbs, The Law of Torts §§26, 27 (2000). 6 See Draft Restatement (Third) of Torts, supra note 2=, §§1, 2. 7 I describe this as the “modern” criminal law conception because the influential Model Penal Code emphasizes this conception. Traditional criminal law doctrine, by contrast, does not employ or emphasize any single conception of negligence. Instead, it contains a variety of doctrines that could be broadly classified as involving negligence—including Page 6 of 57 Simons, Dimensions of Negligence 8/7/02