Did the moral precepts of the Old Law give justification [before God]?

It seems that the moral precepts of the Old Law gave justification [before God] (iustificatio):

Objection 1:  In Romans 2:13 the Apostle says, “For it is not the hearers of the Law who are justified before God; rather, it is the doers of the Law who shall be justified.”  But the ones who are called doers of the Law are those who fulfill the precepts of the Law.  Therefore, when the precepts of the Law were fulfilled, they gave justification.

Objection 2:  Leviticus 18:5 says, “Abide by my laws and judgments; the man who fulfills them will have life in them.”  But a man’s spiritual life comes through justice.  Therefore, when the precepts of the Law were fulfilled, they gave justification.

Objection 3:  Divine law is more efficacious than human law.  But human law gives justification, since there is a kind of justice in the fulfillment of the precepts of the law.  Therefore, the precepts of the Law gave justification.

But contrary to this:  In 2 Corinthians 3:6 the Apostle says, “The letter kills .....”  According to Augustine in De Spiritu et Littera the Apostle is referring here even to the moral precepts.  Therefore, the moral precepts did not give justification.

I respond:  Just as ‘healthy’ is said first and primarily of that which has health, whereas it said secondarily of that which is a sign of health or of that which preserves health, so too ‘justification’ is said first and primarily of the very effecting of justice, whereas ‘justification’ can be said secondarily—and, as it were, improperly—of a sign of justice or of a disposition toward justice.
There are two ways in which the precepts of the Law clearly gave justification, viz., (a) insofar as they disposed men toward the justifying grace of Christ and (b) insofar as they also signified that grace.  For as Augustine says in Contra Faustum, “Even the life of that people was prophetic and a figure of Christ.”
However, if we are talking about justification properly speaking, then notice that ‘justice’ can be understood either as it exists in a habit or as it exists in an act, and so ‘justification’ is predicated in two ways:  (a) first, insofar as a man becomes just by acquiring the habit of justice and (b) second, insofar as he performs the works of justice, in which case justification is nothing other than the execution of justice.
Now as is clear from what was said above (q. 63, a. 4), justice, like the other virtues, can be understood either as acquired justice or as infused justice.  Acquired justice is caused by actions.  By contrast, infused justice is caused by God Himself through His grace; and this is the true justice about which we are now talking and in light of which someone is said to be just before God—this according to Romans 4:2 (“If Abraham was justified by the works of the Law, then he has glory, but not before God”).  Therefore, this sort of justice could not have been caused by the moral precepts, which have to do with human actions.  Accordingly, the moral precepts could not have given justification by effecting justice.
On the other hand, if ‘justification’ is understood as the execution of justice, then all the precepts of the Law gave justification, though in different ways.
For the ceremonial precepts contained justice itself in a general way (justitia secundum se in generali) insofar as they were given for the worship of God, whereas they did not contain justice itself in a specific way except by the specification given by divine law.  And so these precepts are said to have given justification only because of the devotion and obedience of those who observed them.
On the other hand, the moral and judicial precepts contained what was just in it itself either in a general way or also in a specific way.  The moral precepts contained what is the just itself in accord with general justice—which, as Ethics 5 explains, involves “every virtue”—whereas the judicial precepts involved special justice, which has to do with the contractual interchanges (contractus) of human life that take place among men in their dealings with one another.

Reply to objection 1:  The Apostle is using ‘justification’ here to refer to the execution of justice.

Reply to objection 2:  A man who observes the precepts of the Law is said ‘to have life in them’ in the sense that he does not incur the punishment of death that the law afflicts on those who transgress it.  This is the Apostle’s meaning in Galatians 3:12.

Reply to objection 3:  The precepts of human law give justification by means of acquired justice, which we are not discussing at present; rather, we are talking only about that justice which is justice before God.