One of my favorite jobs as a judicial law clerk was writing jury instructions. The legal jargon of the statutes and the case law was created by legislators (often lawyers) and judges (formerly lawyers). The purpose of the statutes and cases was to implement a public policy, something that is supposed to reflect the will of the governed, the average person.
Jury instructions attempt to reduce the rules and criteria embodied in that law and decisions
into ordinary language, understandable to most jurors, normal people. Similarly, there is a move in government documents and in contracts to shift toward simpler language, less jargon. Far to go.
Much jargon is a form of shorthand. When we say mandamus, legally trained folk have a quick understanding of what is meant without having to recite the sentence that explains its meaning. Some other types of terms or phrases are an attempt at precision, locking in a criteria and leaving little room to err. Ironically some of these are called magic language by lawyers, a recitation that must be there for the document to have force or effect. For example, a trademark application must assert that the mark is or will be used in commerce. That has a very specific and set meaning to a trademark lawyer.
We deal with jargon in a wide variety of fields. Why not law? We deal with complex constructions and parse them out. Again, why not law?
Clearly we do not want to stray into legal interpretation. The reason there are lawyers, and not just fact finders and law enforcers, is that there is a wide range of legal interpretation that can be brought to both the law and documents that reflect or invoke the law. This is especially true in common law countries, such as the US and UK, and many other English speaking countries. But opinion is not our purview anyway.
There is a range of questions that deal with legal terms that do have correct answers without digging deeply into legal analysis. This is especially true of jargon and questions about construction. It also could cover etymology since so much legal phrasing comes from variants of Latin, French and early (or earlier) English.
Let's keep the field open and sort between the questions that are appropriate and those that stray too far into legal opinion. We seem to have little problem shutting down individual questions that depart from our bounds.