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Wednesday, May 17, 2006

Why the Necessity Defense is Unneccesary

From a deterrence standpoint, I've never understood why there is such a thing as a necessity or duress defense in criminal law. The deterrence view of criminal law is that we choose punishments to deter judgment-proof individuals from committing acts that harm social welfare. If this is the case, then why bother with the necessity defense.  A harmful act is a harmful act, whatever the reason it was committed. There is no reason to allow harmful acts because we think the reasoning behind them was good.

Suppose a car with a deathly-ill passenger races through a red light en route to a hospital. If the driver was "charged" with the crime, she could plead necessity and get off with nothing. But the fact remains that she went through a red light and caused social harm. Accidents are more likely because of the violated red, however good the motive behind the violation. So I would argue that we should get rid of the necessity defense in this context. 


If we charge the driver with running the red light, then she would still probably run the light; the benefit of getting to the hospital sooner exceeds the cost of the ticket. In other words, the social benefit of the violation is greater than its cost. But this is not a reason for dropping the necessity defense. We want the driver to weigh the cost of running the light against its benefit. The best way to do that is to exclude the necessity defense and let the driver make the determination.

This analysis echoes the strict liabilityvs. negligence debate in tort law. The necessity defense is basically a negligence defense. The driver may have caused harm, but she wasn't negligent, and therefore she should get off. I am arguing for strict liability. If you run the red, you pay the penalty, even if we think running the red was a good idea. When it comes to dangerous activities (such as running red lights), strict liability has some big advantages (such as its ability to engender efficient activity levels). Basically, dumping the necessity defense is the best way to insure that "desirable" crimes are only committed when they are truly desirable.

I can think of several objections to this argument. One is that we don't want to give someone a ticket as they are racing to a hospital. This is true, but we could just give them the ticket later. A second is that part of the social harm of crime is its psychic cost and that a necessary crime has a lower psychic cost. I agree, but this is not a reaon to forget about the other costs. I am less outraged by someone running a red light while going to the hospital than someone running a red light for the fun of it, but there are still real costs to running a red light in any context.

Finally, I must concede that criminal law is not just deterrence based, and the necessity defense may have nothing to do with deterrence. I can't argue with that, other than to say that non-deterrence based tenets of criminal law have real costs, and that we shouldn't take these costs on without at least thinking about them.

Posted by Yair Listokin on May 17, 2006 at 05:30 PM in Criminal Law | Permalink


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You're not weighing all the social harms in your deterrence argument: namely, the harm to the person being rushed to the hospital. We could fear, in part, that some people facing criminal liability might not run that red light, to the detriment of that person in the back seat. Why should that not count as a deterrence-based justification for the necessity defense?

Posted by: Dave | May 17, 2006 5:50:47 PM

Okay, I'll play the law and econ game with someone clearly better at it than me. Why not? Here goes:

Wouldn't abolishing the necessity defense in cases like that deter people from helping strangers even where that is "efficient"? A will not only run a red light but even steal a car to get herself or her mom to the hospital, because the net benefit accrues to her or her loved one. But say a stranger needs medical attention. If stealing the car is costless for A, she'll do it even if she's only minimally decent. But if it isn't, the cost falls on her and the benefit accrues to someone else. Even if a virtuous person would take the hit and give the stranger all the benefits, we're still making it a lot harder for her to make that choice. I'm sure I'm missing something, so let me know what it is.

Posted by: Adil Haque | May 17, 2006 5:51:01 PM

There's a bunch of preliminary problems with this argument I think.

1. Distributive consequences. Need I say more? Perhaps I do. Isn't it the case that "necessity" defenses are raised by those who are in the least-well-off positions in society? Nobody raises a necessity defense for insider trading, but the loss of the necessity defense for fighting off a mugger (a.k.a. "self-defense" -- and lets not forget that this is a necessity defense too) will fall disproportionately on those in crime-ridden neighborhoods. The loss of the necessity defense for running red lights will disproportinately impact those who can't afford to take months off work and hole up in hospitals well in advance or pay ambulances or have private care. Etc.

In a related vein, why should people have to internalize certain costs, and how could they be redistributed? I'm going to call on the self-defense thing again. At bottom, self-defense is unquestionably a necessity defense. However, if I kill you because you're coming at me with a gun, is there any possible just way to impose the cost of this killing on me in the form of prison time? It's cold comfort to me in my cell in Attica that I made a nominally efficient decision to not let the attacker kill me.

2. Why would we think this would change behavior? For the necessity defense to impair the deterrent effect of criminal law, it would have to be the case that there there are a meaningful number of persons X who believe that a set of actions A would not be efficient (because if they believe they are efficient, they'd do it without a necessity defense) and also that the court would erroneously believe it was efficient, thus applying the necessity defense.

Your reply will no doubt be that we should understand the decision process of our hypothetical actor as probabilistic, where the availability of a necessity defense reduces the cost of action X by a factor roughly corresponding to the estimated likelihood that they will prevail in the defense, thus diluting the deterrent effect. However, this requires some heavy assumptions about the decisionmaking process and sophistication of actors who are about to run afoul of the criminal law. Is there any empirical support for the proposition that people consider necessity defenses before they do crimes?

Lately, I've noticed a worrisome trend of economists just assuming cost-benefit decisionmaking methods even for behaviours, such as crimes of passion (or fear) and even sex, that conventionally are largely the baliwick of things better explained by biology or psychology. Isn't it time to take a stand against the economization of the instinctual, hormonal, biological, and reflexive?

3. Wouldn't this cause overdeterrence problems on the margins? In marginal cases, risk-averse actors would undoubtedly shy away from the necessary/efficient crime. Yet the cases where "necessity" defenses might be raised are presumably a very small proportion of all cases (anyone have data saying otherwise?). So the legislature can't lower the fines to compensate for the overdeterrence on the margins without underdeterring the rest of society. How to get around that without an ex post correction? And really, isn't that what the necessity defense is?

Posted by: Paul Gowder | May 17, 2006 9:07:18 PM

Why limit the discussion to deterrence as the foundation of criminal law? Deterrence is only one of the consequentialist justifications for criminal law, and perhaps not even the strongest. Additionally, retribution could be argued as the purpose of criminal law. You cede that there may be other justifications. Doesn't that make the thrust of your post moot? It seems a more apt title would be "Why the Necessity Defense is Unnecessary if We Turn a Blind Eye to the Best Arguments for It."

Additionally, the core of the argument seems flawed. You argue, "dumping the necessity defense is the best way to insure that 'desirable' crimes are only committed when they are truly desirable." This appears to compare apples and oranges. Permitting the necessity defense requires the calculation of social utility absent considerations of the punishment. The question the necessity defense poses is essentially "Was X required to avoid a greater harm?" An objective determination of this question will sufficiently determine the "desirability" of X.

On the other hand, disallowing the necessity defense and thus introducing the punishment into the calculation of utility seems relevant to determining the defendant's utility. Such a subjective determination of X's "desirability" is a far inferior method of weighing social harm for the commission of X. Similar subjectification of the criminal law presented the dilemma manifested in the Goetz case, where the racist got off for shooting 3 African-American teenagers on the subway.

Of course, I don't wish to take issue with a straw-man representation of your argument, so please correct any misunderstandings.

Posted by: Christopher Cassidy | May 17, 2006 9:09:18 PM

Truly great comments. Dave and Adil and Paul's comment 3 are related (please correct me if I am wrong)-- essentially that there is currently an inefficient amount of people acting to help others and that abolishing the necessity defense will exacerbate the problem. I think this an excellent argument. My only response is that there are many ways to deal with this issue independent of the necessity defense. For example, we could have the government pay the costs of good samaritans, or we could create a cause of action for a good samaritan to collect the costs of their actions from someone who they have helped. Both of these plans will address the inefficient helping behavior problem discussed by Dave and Adil, while retaining the benefits of cost internalization in the more typical case (I think) where people are acting out of necessity to help themselves or a loved one.

Paul-- I share your distributive concerns, I am just unconvinced that this is the way to address distributive considerations. Lets assume that those who benefit from the necessity defense are often poor. This doesn't mean the necessity defense is a good thing even from a distributive standpoint. The losers from the crimes protected by the necessity defense will also probably be poor if neighborhoods are stratified by socio-economic status. For example, poor people will be disproportionately harmed by someone running a red light in a poor neighborhood. As for the rationality assumptions here, I have no empirical evidence that people think about the necessity defense. I don't think its unreasonable to suppose, however, that people will be less likely to run red lights in certain circumstances if they know they can't tell the cops and/or court that it was for a good cause.

Christopher, your comment and reference to the Goetz case pointed out a non-economic rationale for getting rid of the necessity defense. Eliminating the necessity defense will eliminate the ability of juries to impose their own subjective standards on criminal trials. If many people are racist, then a necessity defense that essentially appeals to racist notions has a good chance of succeeding. Why give a defendant that chance?

I want to say that I think locking someone up who has a good necessity defense sounds as strange to me as it does to you. But I have no problem with abolishing the necessity defense for criminal fines. And even with respect to prison sentences-- doesn't the necessity defense seem to be the type of thing that should enter into sentencing rather than guilt.

Posted by: Yair Listokin | May 17, 2006 10:56:43 PM


If your proposal amounts to "abolishing the necessity defense for criminal fines," I think you want to abolish something that doesn't currently exist. My sense is that as a practical matter, monetary fines are not a commonly imposed as a form of criminal punishment. Courts rarely impose fines as punishment, as most defendants don't have much money, and when fines are imposed they are only relatively rarely collected (and are usually dwarfed by attorney's fees). For the most part, punishment consists of prison time or probation. There are exceptions to this, of course, but I think they are relatively rare.

Posted by: Orin Kerr | May 18, 2006 12:47:54 AM

I'm no expert on the necessity defence in US criminal law (although from what I've read on it, it is rather similar to the one I know from German law), so correct me if I am wrong, but isn't there something wrong with the premise of the argument, i.e. that such actions _should_ be deterred?

If someone takes an action that leads to some harm in order to avoid a greater harm from happening (that's the reasoning behind the necessity defence, isn't it?), than I don't see why the law should even _try_ to deter, as opposed to accept or even encourage such conduct. After all, on balance, their act does not harm social welfare at all, but indeed furthers it.

(I can see that one might potentially have a problem with this where the person acting avoids harm to themselves by an action that does harm to someone else, but even that would be a question of the correct delimitation of the defence, not a reason to abolish it altogether)

Posted by: Bjoern Elberling | May 18, 2006 7:22:07 AM


Two thoughts. 1. I am not certain if speeing tickets are considered "criminal" fines, but they certainly are in the spirit of criminal law. And even if they are only civil fines, then my argument applies to civil fines, which are not a trivial feature of our justice system. 2. If the criminal justice system is not using criminal fines, then that is a problem in and of itself. Fines are the most efficient means of punishment, far preferable to locking someone up.


You are undoubtedly right, we want people to take actions where the benefit exceeds the harm. But abolishing the necessity defense won't change this. If the benefits of the violation exceed the costs of punishment (which should reflect the social harm), then the individual will still commit the "efficient" violation. The problem is that it is very hard for society to determine what is and is not an efficient violation. By requiring the violator to pay regardless of whether or not the violation was justified, we let the potential violator make the decision rather than having outsiders try to figure it out ex-post.

Thanks to everyone for the insightful comments.

Posted by: Yair Listokin | May 18, 2006 11:04:13 AM


If you want to argue that we should replace our current criminal justice system with a regime of fines, I think that is a novel and provocative idea. I'm a bit curious how it would work, as most defendants have little or no money. Indeed, many are engaging in criminal activity to obtain money (such as those involved in the narcotics trade). Given, that, I'm not sure what you mean when you say that fines are an "efficient" form of punishment. But in any event, such a proposal would certainly be an interesting and provocative idea.

Posted by: Orin Kerr | May 18, 2006 1:28:36 PM


While I think your clarifications re: the applicability of your proposal primarily (only?) to fines rather than to prison sentences, and your openness to the use of necessity defenses like self-defense at the sentencing stage are good things, one must question whether they don't still undermine your overall proposal. After all, if judges and juries are going to be making ex post determinations of efficiency to avoid the harsh results of eliminating the self-defense defense at the sentencing level, then there's no clear reason not to do it at the guilt level as well. Sentencing changes modify the deterrent and distributive effects of a criminal sanction just as much as guilt changes.

Likewise, I don't see how you can make a principled limitation of your position to only the fine context. If we're concerned about underdeterring the crimes for which we impose fines, we should equally be concerned about underdeterring the crimes for which we impose prison sentences. The concerns the various commentators raise apply to fines as well as to prison, though, of course, at a less fevered pitch where the harm to the morally innocent necessary criminal is lighter.

Posted by: Paul Gowder | May 18, 2006 2:20:40 PM

Continuing my masquerade as a consequentialist, I heard that in Scandanavian countries they scale fines to offenders' incomes. That might take you part of the way. Of course fines alone place all the weight on deterrence, none on incapacitation or rehabilitation, so you may want to supplement. Although, from the perspective of reducing crime rates, incapacitation is a less powerful rationale with respect to the demand-driven, profit-motivated crimes that Orin mentions. Lock one offender up, another takes over. By contrast, violent crimes usually require personality traits that have limited representation in the general population. So you lock up murderers, you get much less murder; you lock up drug dealers, you get (roughly) the same amount of drug dealing, holding deterrents (fines, on this proposal) constant. Wow, I have never felt so alienated from a blog comment . . . .

Posted by: Adil Haque | May 18, 2006 2:32:46 PM

Interesting idea! A few thoughts:

1) Why wouldn't a driver weigh the societal costs of running the red light under the current regine? Musn't a rational driver assess whether the social benefit of driving through the light outweights the harm of the sick person not getting to the hospital in order to decide whether to run the light in the first place?

As I understand it, to successfully prove "necessity", a driver must show (essentially), that the social benefit of her actions outweighted the social cost. So, a rational driver should know that if her activity would not be viewed by a court as a "necessity" (if, say, her excuse was that did not want to miss the start of "Grey's Anatomy"), she would not be successful in raising the necessity defense.

2) I'm also not sure I agree that society wishes to deter all red-light running, in the first instance (as your propose seems to assume).

When the legislature enacted the prohibition on running red lights, it presumably was aware of the common-law necessity defense. Further, it seems likely that the legislature envisoned the very scenario you have posited above. As such, the legislature likely saw the defense as part the regulatory regime, in furtherance of the desired social policy of never deterring someone from running a red light in order to rush a sick person to the hospital.

Moreover, it seems likely that the legislature intended that there would be other, very fact-specific situations in which it would be good social policy not to deter someone from running a red light. And the legislature knew it could never predict all of those situations in advance. So, the legislature implemented a strict liability regime but kept the necessity defense -- so that each driver who runs a red light can avoid sanction if she can tell the judge (or arresting officer) a compelling story regarding why it was in society's best interest for her to run the light. Such a regime would, I think, deter more drivers than a negligence regime, but not as many as a pure strict liability regime.

3) Finally, I think your idea of a good samaritarian reimbursement is interesting. But isn't it more efficient for a person who runs a red light to interact with the government once (to raise the necessity defense to either cop, prosecutor or judge, to avoid the vine), than twice (to pay the fine and then put in a claim form to the government for a good samaritarian reimbursement)?

Even if developing a specialized agency to hand out good samarian reimbursements would allow standarization in assessing what good samarian behavior is worth reimbursing (and what is not), it would require creation of an entire bureacracy for this purpose. I'm not sure that is worth the cost of standarization, if that's what we want.

And there still remains the problem of a person who is rushing herself to the hospital. I don't agree that society wants to deter that person from running the red light at all. It is enough to require that person to assess whether or not her injury is sufficiently severe that she could make out the necessity defense.

Posted by: Joe Leahy | May 18, 2006 4:30:50 PM

Again, thanks to everyone for the comments.

Orin and Adil,

When I say that fines are efficient, I mean that they have the potential to deter without requiring the deadweight loss of imprisonment. Judgment proof criminals are definitely an obstacle to a fine-oriented system of enforcement, but that doesn't explain why fines today seem to be completely ignored. Adil's post about income dependent fines suggests one partial solution to the judgment proof problem that is already in use in some countries.


Your comments are right on target. I don't have a principled reason to treat fines and prison sentences differently. My thinking runs as follows, start small (with fines) and see if the results are wacky. If they are, then forget the proposal. If not, then perhaps the necessity defense could be limited for prison sentences as well.


I agree that society wants people to run reds in some contexts. But even if the running of the red is a net gain, there is still some harm (e.g., higher risk of accident). So rather than saying "if the benefit of running the red slightly exceeds the cost, then the violator pays nothing and can run lights with impunity," we should say "the driver gets to calculate whether the benefit exceeds the cost and we are confident that the driver is making a reasonable calcuation because the driver has to pay."
As to the good samaritan reimbursement, there is no question that it requires new bureaucracy and cost and that this weighs against it. I think that it would have benefits beyond the necessity defense, however, so it may be an idea worth exploring in further detail.

Posted by: Yair Listokin | May 18, 2006 10:33:19 PM

Yair writes:

Judgment proof criminals are definitely an obstacle to a fine-oriented system of enforcement, but that doesn't explain why fines today seem to be completely ignored.

If the great majority of defendants are judgement proof, doesn't this explain why fines tend to be ignored?

Posted by: Orin Kerr | May 18, 2006 11:17:45 PM

So your saying your if your loved one got shot in the abdomen. You wouldn't run a red light to the hospital? Even when its 2AM in the morning and nobodys around?

Posted by: Lt. Lam | Jan 20, 2007 2:53:45 AM

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