In his book, Halakhah: The Rabbinic Idea of Law (excerpted in Mosaic), Chaim Saiman aims to explain exactly what halakhah—usually translated as “Jewish law”—actually is. Moshe Koppel writes in his laudatory review:
Saiman notes at the [book’s] outset that halakhah is less than law in that it is neither legislated nor enforced by state institutions and hasn’t been for at least two millennia. He also notes that it is more than law in that it engages its adherents much more thoroughly and intensely than a legal system engages its subjects; no layman goes to hear a lecture on financial regulation, though many go to lectures on Bava Kama, [the talmudic tractate dealing with torts]. . . . This argument is so convincing that it suggests that, if one wishes to explain halakhah to the uninitiated, perhaps law is not the most apt basis for comparison.
The correct comparison, in my opinion, is to a system of social norms, the set of informal rules that, though not enforced by any official bodies, govern our lives much more thoroughly than do laws: how to dress for an occasion, where to stand in conversation and what to say, when gifts are required and what is an appropriate gift, to whom to show deference and how, table manners, workplace interactions, phone etiquette, dating rules, and on and on.
Halakhah is a lot more like a system of social norms than like a system of law, along all the dimensions that Saiman mentions. Apart from the fact that such norms are neither legislated nor enforced by the state, they also engage people in much the way halakhah does. The literature on social norms includes codes (Emily Post and wannabes), responsa (agony aunts and self-styled ethicists in newspapers), and learned novellae by legions of academics. And if people don’t often flock to lectures on the ins and outs of social norms, it’s only because such lectures are unnecessary. The pop culture they consume, from self-help books to Hollywood movies and television sitcoms, already consists of thinly-veiled morality tales designed precisely to instruct them in current standards of appropriate behavior and warn them of the consequences of failing to comply.
To be sure, I am not suggesting that halakhah is simply another system of social norms and nothing more need be said. Obviously, committed Jews regard violating the laws of Shabbat as a more serious matter than belching at the dinner table. [And], as Saiman illustrates at great length, the literature on halakhah through the generations relates to halakhah as if it were legislated and enforced, even if in fact the relevant institutions have been in abeyance for a few millennia.