The defining characteristic of justice is fairness, and even though the idea of justice in courts of law has evolved from the days of trial by ordeal, when it was thought that God would enable the righteous to prevail against all odds, fairness is the basic measure that other legal issues are measured against.
Most people arrive at their basic ideas about fairness by ten years of age.
By the age of ten, most people understand that they should not lie, cheat or steal, or do anything to hurt another human being. It is what human beings learn after their tenth year that is responsible for most of the unbalanced conditions, whereby responsible adults knowingly violate the needs and rights of others for their own benefit, usually justified by elaborate fictions based on the idea that life is a jungle, etc. The rules of process are governed by the jurisdiction of the courts, so that process service is governed by state law, unless the jurisdiction is federal, and then service of process is governed by federal law. Technically a case can be overturned on the basis that service of process was not valid. In civil cases, however, where money or property hang in the balance, then judgments have been set aside on the basis that the original service was not legal.