Why were some Germanic law compilations called pactus agreements?

In the context of Germanic law, some legal compilations were referred to as a pactus (or "agreement") because they represented a collaborative effort between the king and the people.1

While the initiative to declare law typically originated with the monarch, the resulting codes—known as the Leges Barbarorum—generally required the approval of popular assemblies to be considered valid. This collaborative process between the ruler and the tribal members led to the designation of these compilations as agreements.1

It is important to note that this was not universal; for instance, Visigothic laws were an exception, as they were formulated by the king and chief landowners without the participation of the popular assemblies. Over time, as royal authority grew, kings began to move away from this collaborative model, eventually legislating unilaterally through edicts and ordinances rather than through these negotiated agreements.1