Legalism is the law proclaimed from on high, while the common law is organic law that arises from the real-life conditions of the people. From Eric Peters at ericpetersautos.com:

One of the greatest perplexities – and iniquities, if you’re a thoughtful person – is this business of “the law” being “the law.” Meaning, what matters to “the law” (and those who enforce it) is not whether a given thing is morally wrong but only that a law has been violated. This concept flies full-force in the face of common law tradition, which goes way back to before the Norman conquest of England. The basic idea underlying common law is something we – as a people – have forgotten and it is the idea that harm ought to be proved in order to prove that a crime has occurred.
More specifically, that someone – as opposed to some thing – has been victimized by the actions of the accused. That the accused’s actions have, in some way, resulted tangible harm to a victim, who was understood to have to be an actual human being rather than a construct such as “the state of Virginia” or “The United States vs. . . ” Most people here those words and think nothing odd about them. Worse, they think tjere might be something right about them.
But if harm done cannot be substantiated, then how can it be said a crime has been committed?
This a question that underlies the old – now forgotten – legal tradition.
That was before the rise of legalism, which is similar to rigid adherence to the strictures of the Old Testament or the Talmud. They encompass the idea that “the law” is “the law” and must be obeyed and enforced because it is “the law.” Not because it even makes sense. Just because it is. This is the kind of law that currently governs the United States and indeed, the entire Western world. It is a warren of case law, each new case giving something new for legalist to parse over, endlessly.
