Should human law be made in a general way or for particular cases instead?

It seems that human law should not be made in a general way (non debeat poni in communi), but should be made for particular cases instead (sed magis in particulari):

Objection 1:  In Ethics 5 the Philosopher says, “Legal justice consists in everything that is posited by law for individual cases, as well as decrees,” which are likewise particular, since decrees are issued for particular actions.  Therefore, law is made not only in a general way, but also for particular cases.

Objection 2:  As was explained above (q. 90, a. 1‑2), the law directs human acts.  But human acts are particulars.  Therefore, human laws should not be made in a general way, but should be made for particular cases instead.

Objection 3:  As was explained above (q. 90, a. 1-2), law is a rule and measure of human acts.  But as Metaphysics 10 puts it, a measure should be fixed with certitude (certissima).  Therefore, since in human acts there is nothing general that is fixed to such an extent that it does not fail in some particular instances, it seems necessary for laws to be made for particular instances instead of being formulated in a general way.

But contrary to this:  The Legal Expert says, “Laws have to be made for situations that come up very frequently, but laws are not made for situations that can come up perhaps only once.”

I respond:  If something exists for the sake of an end, then it must be proportioned to that end.  Now the end of law is the common good, since, as Isidore says in Etymologia, “Law must be written for no one’s private advantage, but for the general welfare of the citizens.”  But the common good is built up out of many things.  And so the law must take into consideration a multiplicity of persons, actions, and times.  For a civil community is composed of many persons, and its good is procured through a multiplicity of actions, and it is instituted not just to endure for a brief time, but to last for all time through a succession of citizens, as Augustine puts it in De Civitate Dei 12.

Reply to objection 1:  In Ethics 5 the Philosopher posits three parts of legal justice, i.e., positive law.
Some laws are made in an absolutely general way, and these are the general laws (leges communes).  It is with respect to laws of this sort that he says that what is legally just is such that at the beginning it does not matter whether it is this way or some other way, but that it does matter once the law is made—e.g., that prisoners should be ransomed for such‑and‑such a mandated price.
On the other hand, there are certain laws that are general in one respect and particular in another respect.  Laws of this sort are called privileges (privilegia)—private laws (privatae leges), as it were—since they have to do with particular persons; and yet they are such that their force extends to many actions.  It is in this connection that he adds, “..... everything that is posited by law for particular cases.”
Again, certain things are called legal not because they are laws but because they involve the application of general laws to particular cases—for instance, decrees (sententiae), which are treated as laws.  It is in this connection that he adds, “and also decrees.”

Reply to objection 2:  That which directs must direct a plurality of things.  This is why in Metaphysics 10 the Philosopher says that everything belonging to a given genus is measured by some one thing that is first in that genus.  For if there were as many rules and measures as there are things ruled and measured, then rules and measures would cease to be useful, since their usefulness consists in making it possible for many things to be understood on the basis of some one thing.  Likewise, a law would not be useful if it did not extend beyond some one particular act.  For as was explained above (q. 92, a. 2), it is the particular precepts of prudent men that are given for the purpose of directing particular acts, whereas a law is a general precept.

Reply to objection 3:  As Ethics 1 says, we should not seek the same sort of certitude in all things.  Hence, in contingent matters such as natural and human affairs, the certitude that something is true in most cases is sufficient, even if there if a few exceptions occur now and then.