Modern "Reformed" theology in some circles has adopted an understanding of the general equity that is quite contrary to what the Westminster Divines meant when they wrote XIX.4,
To them also, as a body politic, he gave sundry judicial laws, which expired together with the state of that people, not obliging any other, now, further than the general equity thereof may require. (Westminster)
To them also he gave sundry judicial laws, which expired together with the state of that people, not obliging any now by virtue of that institution, their general equity only being still of moral use. (Savoy)
To them also he gave sundry judicial laws, which expired together with the state of that people, not obliging any now by virtue of that institution; their general equity only being of moral use. (1689)
As documented here and here many moderns have understood "general equity" to be only explicating the crimes that are to be punished, but not what the punishments are to be or have even removed general equity from civil law altogether and confined it wholly to the church (thus, collapsing the 2-Kingdoms, creating a kind of one-kingdom ecclesiastical antinomian theonomy). This is not, of course, what the Reformers meant by general equity (which is the natural or moral law that is written on all men's hearts and forever binds all). As these posts argue (see also here: https://reformedbooksonline.com/topics/topics-by-subject/covenant-of-grace/the-mosaic-covenant/the-civil-law/ ), the Reformers understood the general equity of capital civil crimes to forever bind all. While the mode of execution may differ according to times and circumstances, the general equity (i.e. the moral law demanding the death penalty for such crimes), remains forever immutable. This is very clear in Reformers like Junius (who wrote the greatest treatise on civil law), Beza (who coined the term "general equity"), and Piscator (who's commentary on Exodus stands behind XIX.4) and I am unsure how a different interpretation could have possibly arisen. While I am neither a Kuyperian nor a Covenanter (though I have much affinity with Covenanters, as all Christians should given that they were instrumental in writing Westminster), these two sources are some of the few I have found that see this issue and accurately represent what the Reformers meant by "general equity" when they wrote the Confession. The issue with those who oppose these Kuyperians and Covenanters is not their biblical theology (which is a correct criticism, as I believe the Bible teaches a 2-Kingdom view of government), but their natural theology/law (which says that the death penalty for murder, adultery, sodomy, bestiality, kidnapping. delinquent children is demanded, as all men know from the light of nature); Escondido is incorrect in their natural, not biblical theology. I want to be absolutely clear on this point. My argument (and Junius') does not rest on your covenant theology. One can be anything other than a Marcionite and affirm our argument. The reason for this is because covenant theology cannot change natural law. This is the Confessional view of general equity and we can see that it is so by reading those who wrote the Confession and those whose theology stands behind what they wrote. One of those men is Franciscus Junius. Here we have Junius clearly teaching that the general equity of capital crimes under the Mosaic Law demands the death penalty for such crimes today, though the mode of execution may vary:
Regarding Junius's final comment about exceptions, it is somewhat hard for me to express this well at the moment, but I wish to emphasize that what Junius says here is not contradictory to what he has said previously about the universal applicability of capital crimes. The reason is that such crimes ought always to be capital in ordinary circumstances. It may be said that the substance of the punishment is not actually eliminated because the law intends a different thing and thus in a way the crime is altogether a different crime with a different punishment annexed. For instance, the Puritans had a law that sodomites are to be put to death and this is the substance of the law against sodomy, but if the offender was a boy under 14, he would be whipped instead. It may then be argued that one can do this because the moral equity of the law against sodomy is intended for those who are adults. Whether such a mitigation would be legitamate, I suppose is where the debate would be. But the principle itself is no different from what we do in ecclesiology with the sacraments or with excommunication for instance (in which it is commonly affirmed that the matter of the sacraments may be switched out if someone has some sort of disease that prevents them from taking it or if the materials are lacking or with excommunication that a man ought not to publicly excommunicate his own parents or a civil magistrate) where certain things ought always to be done in ordinary circumstances but extraordinary circumstances call for a different approach. See especially William Perkins on Christian Equity.