I've studied this legal paradox more than most lawyers, that is, I've spent a couple of hours thinking about it.
Here's the paradox: Lawyers say they judges are not supposed to "legislate from the bench" on a regular basis. People from all sorts of legal traditions say this on a regular basis. So that's strong evidence that most lawyers agree that the law is set down by the makers of the law (the legislature) and then the courts apply those laws.
Yet at the same time, the courts develop all sorts of policies. The most dramatic example is that, in an effort to keep police from stepping on civil rights the Supreme Court decided that throwing out evidence obtained from civil rights violations is "inadmissible." If the country, or a state, has a problem with cops over-stepping their bounds you would think that the legislature would handle it. The legislature can develop all sorts of incentives--from firing cops to suspensions to jail time--to punish cops of that violate protocol. But the court decided not to leave it up to the legislature how to punish these acts, because it was going to handle it.
Of course that is not an isolated incident. The courts develop all sorts of protocols on how laws are to be enforced and understood that regularly violate the intent of the legislature, with the justification that it is part of the function of the judiciary.
This strikes me as the central paradox of law. The law is meant to be written by the legislature because they make the laws, but at the same time because they can't be clear about everything judges are supposed to reinterpret the laws (often clearly in ways at odds with the intent) so as to improve them.
It closely parallels to the two central tenants of the microeconomics: (1) people are rational actors that make optimal decisions, and lots of economic papers rationalize all sorts of behavior in that framework and (2) economists know better than people because they have better data, so we can explain all sorts of irrational behavior people make and how to improve on it.
In both cases the obvious question is, how do you tell case 1 from case 2? How do I know when I'm supposed to insist the legislature (or people) were doing what is best and how do I know if they made a mistake and only I the lawyer (economist) with my superior reasoning ability can correct them? I know the answer in economics is "we don't have a fucking clue, this is a paradox" but you get the sense lawyers are supposed to have (very simple) rules for separating the two cases since they have (very simple) rules for everything else.