The legislator ought, as much as possible, to determine everything relating to punishments, for two reasons: that they may be certain, and impartial.
I. The more completely the scale of punishments is rendered certain, the more completely all the members of the community are enabled to know what to expect. It is the fear of punishment in so far as it is known, which prevents the commission of crime. An uncertain punishment will therefore be uncertain in its effects‹since, where there is a possibility to escape, escape will be hoped for.
II. The legislator is necessarily unacquainted with the individuals who will undergo the punishment he appoints; he cannot, therefore, be governed by feelings of personal antipathy or regard. He is impartial, or at least, appears to be so. A Judge, on the contrary, only pronouncing upon a particular case, is exposed to favourable or unfavourable prejudices, or at least, to the suspicion of such, which almost equally shake the public confidence.
If an unlimited latitude be allowed to Judges in apportioning punishments, their functions will be rendered too arduous: they will always be afraid either of being too indulgent or too severe.
It may also happen, that being able to diminish the punishment at discretion, they may become less exact in requiring proof, than if they had to pronounce a fixed punishment. A slight probability may appear sufficient to justify a punishment which they may lessen at pleasure.
There may, however, often arise, either with regard to the offenses themselves or the person of the delinquent, unforeseen and particular circumstances, which would be productive of great inconveniences, if the laws were altogether inflexible. It is therefore proper to allow a certain latitude to the Judge, not of increasing, but of diminishing a punishment, in those cases in which it may be fairly presumed, that one individual is less dangerous, or more responsible than another, since, as has been before observed, the same nominal punishment is not always the same real punishment. Some individuals, by reason of their education, family connections, and condition in the world, presenting if we may so speak, a greater surface for punishment to act upon.
Other circumstances may render it expedient to change the kind of punishment; that which has been directed by the law may be incapable of application, or it may be less suitable in other respects.
But whenever this discretionary power is exercised by a Judge, he ought to declare the reasons which have determined him.
Such are the principles. The details of this subject belong to the Penal Code, and to the Legislative Instructions to the Tribunals.