The Preventive Theory

In one line

Punishment is justified because it disables the offender from offending again, by removing him from society, from his occupation, or in the extreme case from existence.

The claim

The preventive theory, sometimes called the incapacitative or disabling theory, is forward looking like deterrence and different from it in one respect that decides everything.

Deterrence works on the will. It leaves the offender able to offend and gives him a reason not to.

Prevention works on the capacity. It does not care what the offender chooses, because it has arranged that his choice cannot take effect.

Once that distinction is fixed, the rest of the theory follows. Imprisonment prevents while it lasts. Disqualification from driving, from holding office, or from practising a profession prevents in a narrower field. Forfeiture of the instruments of an offence prevents by removing the means. And the death penalty prevents absolutely, which is the only claim made for it that no one disputes.

Its strengths

It works whether or not the offender is rational. The objection that deterrence assumes a calculating offender does not touch prevention. A person who cannot be frightened can still be confined.

Its central claim is not speculative. Whether a sentence deters is a contested empirical question. That a prisoner cannot commit a burglary outside the prison is not.

It explains the sentences that puzzle the other theories. Disqualification, forfeiture and licence conditions are hard to describe as deserved and unlikely to deter. They are straightforwardly preventive.

And Indian law uses it openly. Among the mitigating circumstances the Constitution Bench accepted in Bachan Singh v. State of Punjab, (1980) 2 SCC 684, is the probability that the accused would not commit criminal acts of violence as would constitute a continuing threat to society, and the Court placed on the State the burden of proving by evidence that the accused does not satisfy that condition. A mitigating factor framed as a prediction about future dangerousness is preventive reasoning written into the law of capital sentencing. Machhi Singh v. State of Punjab, (1983) 3 SCC 470, in the passage where it explains the collective conscience, puts the preventive case in the community's own voice: that when the community feels that for the sake of self preservation the killer has to be killed, it may withdraw its protection.

Its weaknesses

It looks to the future and therefore punishes for what has not happened. Desert is knowable. Dangerousness is a prediction, and predictions of future violence are notoriously unreliable. Sentencing on them means holding people for what they might do.

It has no upper limit, and its logic runs longer than deterrence. If the justification is incapacitation, the sentence should last as long as the danger, which for some offenders means for ever. Deterrence at least stops when the message has been delivered.