Probably the main reason you’ve found this subject difficult to research is because it’s based on the assumption that there are cohesive grounds on which to base questions like, say, “laws in Medieval times” or “laws in Medieval Europe.” In the former case, your search will be frustrated by the fact that laws and the formation thereof varied hugely throughout the period we understand as “Medieval.” In the latter, you will be similarly stymied because there was no unified body creating law throughout “Europe.” Not only is the formation of law significantly different between, say, England or France, much of what you might recognize as England or France today is wildly different from the borders that bounded both during the timeline in question. And no one in either place, or any of the adjacent spaces, would have identified themselves as a unified body of peoples known as “Europeans.”

All that being said, you might find similarities that run through certain parts of certain periods in some locations of Medieval Europe — but your question is still roughly equivalent to someone asking “How were laws made in the Northern Hemisphere in the Twentieth Century?” The answer will invariably be, “It depends on what region and what decades you’re referring to, and you’ll still need to know what came before to really grasp what followed thereafter.”

There are a lot of folks in r/AskHistorians who would love to answer this question, but it has to be formulated more clearly before they can. Narrow in on a more specific time period or location, recognizing that the world was as widely and wildly different in the Thirteenth Century as it is today, and we’ll be off to the races.