Under what law is civil case?

Both the Federal and state systems have civil case law. Case law is that derived from previous cases decided by appellate courts, with the result published in an opinion. Any system which has appellate courts with published opinions usually has civil case law. Civil, as opposed to criminal. This is because the legislature has not written laws to cover every possible case, but controversies between people are infinitely varied, and where cases come to court and there is no act of the legislature on point, the parties are still entitled to have their case decided. In these instances the court must provide "judge made law", which then becomes "precedent" and is binding in all subsequent cases of similar or identical facts, unless and until the legislature goes ahead and passes laws on those points.