Why is our system called the federal system or dual-sovereign system?

Suppose the federal Congress and a state legislature have identical criminal statutes. This issue is called "dual sovereignty" because the original thirteen states were separate political entities until they joined the federal union and gave up some of their sovereignty to the federal government.

answer; ///he or she can either go to court or not. if he or she doesn't go, he or she must send a witness to stand for them, if he or she doesn't send a witness, he or she will be issued a bench warrant ,captured and forced to go to court; good luck

trade regulation is a field of law, often bracketed with antitrust (as in the phrase “antitrust and trade regulation law”), including government regulation of unfair methods of competition and unfair or deceptive business acts or practices. antitrust law is often considered a subset of trade regulation law. franchise and distribution law, consumer protection law, and advertising law are sometimes considered parts of trade regulation law.

in general the theory of economics says that the more open to trade a country is the better   the result for the same country and the whole economies.

in real life countries impose taxes, quotas, etc which is not so good for the economies.

this kind of commercial war between the usa and china is slowing down the growth of the whole world so we can say that it is a draw back of trade regulations. and the free trade agreements are benefits of trade regulations.