I'm using orthogonal in the sense of "can vary independently". IOW, something can be illegal but yet still be ethical, while something could be legal but still be unethical.
Of course, this is all somewhat subjective, and I acknowledge some people may dispute the idea that something can be illegal and still be ethical. But if a law is bad, I believe breaking that law can be ethical behavior. YMMV.
while they can vary independently because they are dis-similar, as a general rule it seems they are complementary more often than not. So, I would say they are likely co-vary together (even if inversely) at times.
At an intutive level, "ethical fabric" is often/practically seen substitute for legal/regulatory infrastructure. The latter is more complex/arduous/expensive, so one advantage of developing ethical norms is increased productivy (from more focus on business, less on due dilligence/monitoring of contracts and general micro-management issues).
Ethics in business are simply informal rules.
The purpose is to fill in gaps in the laws.
(or mitigate the cost of a hyper-specific compliance regime).
Thus, legal systems underpin the context for "informal ethics" in this sense.
"Moral ethics" (so called) are a wholly distinct concept.