folklore = folktales, fairy tales, knowledge (sometimes right, sometimes wrong) passed by word of mouth It's hard to guess without the full context, but I assume the author is talking about some law, or some approach to making laws. In that context: legal folklore = folklore in the legal field (jurisprudence, having to do with the law, judges and so on) So the author is critizing some idea (which you didn't tell us about) as "legal folklore" in a negative, deriding way. He is saying that that idea is just passed from mouth to mouth by tradition, but the idea itself has no firm basis to stand on, and has no place in modern society at all.

= It is nothing other than legal folklore. The rest you'll have to understand form context.

i dont know either