Does Punishment Deter? The Evidence
Chapter Thirty
Syllabus topic 2, "Theories of Punishment"
Pages 120 to 123 of 806
In one line
The one question in this subject with an empirical answer is whether punishment deters, and the answer is that certainty of detection deters, severity of sentence deters very little, and neither deters the offences people most want deterred.
In the wording a student can write in an exam: the deterrent effect of punishment depends far more on the perceived certainty of detection and conviction than on the severity of the penalty. That finding is consistent across jurisdictions and across offences, and it was stated as a principle by Cesare Beccaria in 1764 before any of the modern research existed. Severity has a small deterrent effect at the margin and none at all on offences committed impulsively, in intoxication, in rage, or by offenders who do not expect to be caught.
Why a chapter on evidence belongs in a law paper
Because the deterrent theory makes a factual claim, and a claim that can be tested ought to be. This is also the cheapest way for a candidate to raise the quality of an answer. Everybody writing about the death penalty asserts that it does or does not deter. A candidate who explains why the question is hard to answer, and what the answer turns on, is doing something different.
Certainty against severity
Beccaria's proposition, 1764. It is not the intensity of punishment that has the greatest effect on the human mind, but its extent; and the certainty of a punishment, even if moderate, will always make a stronger impression than the fear of a more terrible one united with the hope of impunity.
Why it is right. A potential offender's calculation involves a probability and a magnitude. Where the probability of being caught is low, multiplying the magnitude changes the expected cost very little; where it is high, even a moderate penalty is a real cost. Doubling a sentence that will probably never be imposed changes almost nothing.
Why it matters in India. The lever Indian legislative practice reaches for is severity, because raising a maximum sentence costs nothing and can be done in an afternoon. Raising the certainty of detection requires investigation capacity, forensic capacity, prosecutorial capacity and court capacity, which cost money and take years. So the cheaper lever is pulled and the effective one is not.
What the evidence supports
Stated carefully, because overstating it is as bad as ignoring it.
Certainty has a measurable deterrent effect. Increases in the perceived probability of detection are associated with reductions in offending across many offence types.
Severity has a small effect at best. Studies of sentence length changes generally find little or no reduction in offending attributable to the increase.
Celerity, that is promptness, matters. A penalty that follows quickly on the offence is more effective than the same penalty long delayed, which is Beccaria's third condition and which bears directly on Indian court delay.
Does Punishment Deter? The Evidence
Some offences are undeterrable in practice. Offences committed in rage, under intoxication, by persons with serious mental illness, and by those who do not expect to survive the act, are outside the theory's reach whatever the penalty.
Imprisonment may increase reoffending. There is evidence that short sentences of imprisonment for lesser offences are associated with higher reconviction rates than community disposals for comparable offenders. That is the opposite of special deterrence and it is one of the main arguments for probation and for community service.
The methodological difficulty, stated honestly
A candid answer says why the question is hard, and there are four reasons.
The comparison is with a counterfactual. To know whether a penalty deterred, one has to know how many offences would have happened without it, which is unobservable.
Offence rates move for many reasons. Demographics, employment, urbanisation, policing and the willingness of victims to report all move at once, and separating the penalty's contribution from the rest is very difficult.
Reported crime is not crime. A change in policing that raises detection also raises recorded offences, so a successful enforcement policy can look like a rise in crime.
Perception is what matters and it is not measured. Deterrence works through what potential offenders believe about their chances, not through the true probability, and belief is rarely measured at all.
The death penalty, which is where this argument is actually used
MU sets the merits and demerits of the death penalty on four printed papers and the deterrence claim is the first argument on the retentionist side.
Three things can be said with confidence and they should be said in that order.
No study has established that capital punishment deters murder better than long imprisonment does. The comparison is between two severe penalties and the marginal difference, if any, has not been demonstrated.
The reason is structural. Murder is very often committed in circumstances in which no calculation occurs, so the marginal severity of the penalty has nothing to act on.
And the certainty of detection for murder is what varies. Where a murder is very likely to be detected and prosecuted, the deterrent work is already done by that likelihood.
The Law Commission of India considered the deterrence evidence when it recommended abolition except for terror offences, and its treatment is dealt with in [What the Law Commission Has Recommended].
A worked example
Two proposals to reduce theft from railway passengers in Mumbai.
Proposal A. Raise the maximum sentence from three years to seven.
Proposal B. Put more officers on the platforms and on the trains, and provide for immediate charging.
Does Punishment Deter? The Evidence
What the evidence predicts. Proposal B works and Proposal A does not, because A raises the magnitude of a penalty that is unlikely to be imposed while B raises the probability that it will be.
What Bentham would add. If B achieves the reduction, then A is needless within the meaning of his rule, and needless punishment is unjustified.
What Beccaria would add. B also improves celerity if the charging is prompt, and promptness is his third condition.
What a court can do. Nothing about either. This is a question for the executive and the legislature, and the fact that the courts cannot reach it is one reason sentencing reform on its own achieves so little.
What beginners get wrong
They say deterrence does not work. It does work; certainty works. What has little effect is severity.
They say the evidence proves the death penalty does not deter. The honest statement is that no study has established that it deters better than long imprisonment, which is a different and defensible claim.
They confuse deterrence with incapacitation. A long sentence prevents offending during the sentence whether or not it deters anybody, and the two effects have to be separated before either can be assessed.
They cite figures they cannot source. An answer that quotes a specific percentage without a source is worse than one that reasons carefully without figures.
Quick revision
- Certainty of detection deters; severity of sentence deters very little; promptness matters.
- Beccaria 1764: the certainty of a moderate punishment makes a stronger impression than the fear of a terrible one joined to the hope of impunity.
- Undeterrable in practice: offences committed in rage, under intoxication, by the seriously mentally ill, and by those who do not expect to be caught.
- Short sentences of imprisonment may increase reoffending compared with community disposals.
- Four methodological difficulties: the counterfactual, confounding causes, reported crime not being crime, and perception rather than reality being what matters.
- On the death penalty: no study has established that it deters murder better than long imprisonment, and the structural reason is that murder is often not the product of calculation.
- Indian legislative practice reaches for severity because it is cheap, and for certainty rarely because it is not.
Test yourself
1. State Beccaria's proposition on certainty and severity. That it is not the intensity of punishment which has the greatest effect on the human mind but its extent, and that the certainty of a punishment, even a moderate one, will always make a stronger impression than the fear of a more terrible penalty joined to the hope of impunity.
2. Why does raising a maximum sentence usually achieve little? Because a potential offender's calculation combines the probability of being caught with the size of the penalty. Where the probability is low, multiplying the penalty changes the expected cost very little. Raising certainty raises the whole expected cost; raising severity multiplies a number that is already close to zero in the offender's estimation.
Does Punishment Deter? The Evidence
3. Name three classes of offence that deterrence cannot reach. Offences committed in rage or on sudden provocation; offences committed under intoxication or the influence of drugs; and offences committed by persons with serious mental illness or by those who do not expect to survive the act. In each, no calculation of cost against gain occurs at the time, so the size of the penalty has nothing to act upon.
4. What is the honest statement about the death penalty and deterrence? That no study has established that capital punishment deters murder better than long imprisonment does. That is not the same as saying that it does not deter at all: the claim which has never been made out is the marginal one, that death deters better than the severe alternative with which it must be compared.
The rest of this subject
These notes are cut from the University's printed syllabus. Open the syllabus itself, or the past papers, for the same subject.