Though justice and prudence are inseparable, we must have respect to the ideas of people in general, for they make a distinction between the different cardinal virtues.
48. It is clear also, according to the sacred Scriptures, which are the older, that wisdom cannot exist without justice, for where one of these two is, there the other must be also. With what wisdom did Daniel expose the lie in the false accusation brought against him by his thorough examination, so that those false informers had no answer ready to hand! It was a mark of prudence to convict the criminals by the witness of their own words, and a sign of justice to give over the guilty to punishment, and to save the innocent from it.
49. There is therefore an inseparable union between wisdom and justice; but, generally speaking, the one special form of virtue is divided up. Thus temperance lies in despising pleasures, fortitude may be seen in undergoing labours and dangers, prudence in the choice of what is good, by knowing how to distinguish between things useful and the reverse; justice, in being a good guardian of another's rights and protector of its own, thus maintaining for each his own. We can make this fourfold division in deference to commonly received ideas; and so, while deviating from those subtle discussions of philosophic learning which are brought forth as though from some inner recess for the sake of investigating the truth, can follow the commonly received use and their ordinary meaning. Keeping, then, to this division, let us return to our subject.
Source: On the Duties of the Clergy (New Advent)