This is an interesting passage from John M. Najemy (2006) A History of Florence. It discusses how some forms of law emerged to control the elite.
Elite vendettas were usually directed at families or factions of the same class. Vendetta may be thought of as codified private justice: a system for handling and sometimes resolving disputes without the intervention of law or courts. The thirteenth-century elite’s preference for private justice has generally been explained in terms of codes of honor and structurally ingrained patterns of behavior that demanded retribution for insults or injuries. One theory, which focuses on the ritual dimension of feuding, hypothesizes that feuds were a way of containing conflict within certain limits and rules that made them a mechanism for limiting chaos, for channeling hostilities into actions and reactions that contemporaries recognized as governed by custom and therefore manageable. But it is important to distinguish the intra-class violence perpetrated by elite families against each other from the inter-class violence that particularly provoked the anger of the popolo. Violence against persons outside the elite emerged from class rather than purely factional tensions. Behind much elite violence was the growing antagonism between the elite, which wanted above all to remain master of its own house, and the popolo, which had already begun creating laws, institutions, and forms of public coercion whose first purpose was to rein in the turbulent elite. Although popular governments applied tough sanctions against elite violence in the late thirteenth century, elite vendettas were at least as common at this time as in any previous generation. Much elite violence, whatever the specific origin in this or that quarrel, can thus be seen as collective acts of defiance against the constraints imposed by the popolo: loud statements that the elite wanted no meddling from self-declared governments of guildsmen in what it considered its own internal affairs. From this perspective, the pursuit of vendetta was a politically motivated rejection of the popolo’s emerging norms of the supremacy of law and the internalized discipline of the good citizen.
The elite spent a lot of time and resources fighting each other–always trying to gain some advantage or prove their sense of honor (and to show class autonomy)–but commerce, which was developed by the non-elites, needs more social stability. Business people need to make long-term plans and have some reasonable idea of what the future holds. They needed a sense of security. In other words, they needed to transform danger into risk.