A "Legal System"?
It is my presumption that the primary purpose of a legal system is to govern relations in a society of human beings. How should human beings behave in a society - how do they handle disputes, how do they ensure fair treatment, how do they ensure their rights, etc... In torah-talk this would be "bein adam v'chaveiroh".
It is also true that there are aspects of a legal system that try to legislate "morality" to some degree. Polygamy may be a good example. Not being able to buy liquor on Sunday morning (my favorite pet peeve). In many cases, these are vestiges of a more theocratic society that have been preserved to varying extents in legal systems around the world. In torah-talk this is "bein adam v'hamakom".
I don't know if there is a third category that exists in Halacha or whether it is an overdeveloped case of the latter category, but one of the key things that rubs be the wrong way about calling it a "legal system" is the disproportionate amount of "laws" that seem to be absurd from a legal perspective. What direction to align your bed, which shoe to put on your foot first, how to make tuna salad on Shabbos, how to chase away birds from their nests to take their eggs even if you don't have any need for them. When added up, these seemingly minor grains of halacha add up to enormous boulders. What other legal system exists out there where such minutia are regulated with the force of law?
Which brings me to the next question - the origin of many of these laws. What I am about to state is personal opinion and I am sure many will disagree, but the origins of many of these laws seem quite bizarre. We can talk about Bismark and his line about laws and sausages, but frankly, there has to be a limit? I can certainly buy the concept of certain laws being given as Divine Revelation - we can argue about whether they were or weren't, but there is a huge gap between Divine chukkim and reasoning such as:
"The Scriptural source for this advice is derived from the verse: "The belly you fill with your treasure (Tzfuncha) who have sons in plenty" as if to say that placing one's bed from the "tzafon" (north) will lead to having "sons in plenty". Considering that God's presence is said to hover between east and west, it was felt that engaging in marital relations within this corridor would be inappropriate. Therefore one places one's bed north-south so as to avoid a direct collision with the Shechina during marital relations." (Hirhurim blog)2/05/2008
Which brings me to my final point - it has been argued that Halacha is a flexible system. And perhaps it is more flexible than some people admit. But is it possible to have a legal system where it seems like nothing can ever be admitted to require change? Sure your individual case might get a dispensation, but we can never say, this was a mistake and it needs to be changed for everyone. Imagine the situation in the case of Civil Rights for blacks where the United States never ruled that racial segregation was wrong, and instead they said, well, if you ask your local Board of Education, they can look at your case and perhaps allow it, but on the record it is still enforced?
I don't know, am I completely insane in asking these questions? I am not a lawyer, nor am I a talmid chacham, and really my point is not to criticize Halacha, but to ask "Is Halacha something sui generis, or is it just a variant of a legal system?