In this article, we will discuss the legal system that is followed in the United States of America and other countries and what constitutes in a common law system.
There are two main sources of law, primary and secondary. Newspapers, reports, journals, and treaties become your secondary source of law while case laws, bare acts, etc., become your primary source of law. The American system is a “common law” system, which relies heavily on court precedent in formal adjudications. In our common law system, even when a statute is at issue, judicial determinations in earlier court cases are extremely critical to the court’s resolution of the matter before it. However, some part of the country does not follow the common law system but a civil law system i.e., North America (Louisiana and Quebec), Central and South America.
What is the civil law system? A comprehensive system of rules and principles is usually arranged in codes and easily accessible to citizens and jurists. A well-organized system that favors cooperation, order, and predictability, based on a logical and dynamic taxonomy developed from Roman law and reflected in the structure of the codes. An adaptable system, with civil codes avoiding excessive detail and containing general clauses that permit adaptation to change.A primarily legislative system yet leaving room for the judiciary to adjust rules to social change and new needs, by way of interpretation and creative jurisprudence.
“In 1787, 12 of the original 13 states (except Rhode Island) sent delegates to a constitutional convention where they drafted the document that became the US Constitution. The delegates included public leaders such as George Washington, Alexander Hamilton, Benjamin Franklin, James Madison and Roger Sherman. John Adams and Thomas Jefferson were representing their country in England and France. To become effective, nine states had to ratify the document. The ninth state ratified the document in 1788, and it became effective in 1789, replacing the Articles of Confederation, the governing document that preceded it.”
Essential of Common Law System:
- Relies on Precedents:
- Case laws are judge-made laws, and as such it is easy for courts to rely upon prior court decisions (precedents). This principle is also known as Stare Decisis – that mandates a lower court follow the decisions of a higher court. The decisions or final judgments by the judiciary are final and legally binding on all parties involved in a dispute.
- Court Hierarchy and Jurisdiction:
- The federal court system, for instance, is based on a three-tiered structure, in which the United States District Courts are the trial-level courts; the United States Court of Appeals is the first-level court of appeal; and the United States Supreme Court is the final arbiter of the law. The American legal system is based on a system of federalism, or decentralization and while the national or “federal” government itself possesses significant powers, the individual states retain powers not specifically enumerated as exclusively federal.
The United States of America encompasses both codified and uncodified laws. It is a federal structure system and seeks power from the Constitution that is superior to all. The Constitution sets out the boundaries of federal law, which consists of Acts of Congress, treaties ratified by the Senate, regulations promulgated by the executive branch, and case law originating from the federal judiciary. The USC (United States Code) is a codified version of statutory laws.
Federal law and treaties, so long as they are in accordance with the Constitution, preempt conflicting state and territorial laws in the 50 U.S. states and in the territories. However, the scope of federal preemption is limited because the scope of federal power is not universal. In the dual sovereign system of American federalism (actually tripartite because of the presence of Indian reservations), states are the plenary sovereigns, each with their own constitution, while the federal sovereign possesses only the limited supreme authority enumerated in the Constitution. Indeed, states may grant their citizens broader rights than the federal Constitution as long as they do not infringe on any federal constitutional rights. Thus U.S. law (especially the actual “living law” of contract, tort, property, criminal, and family law experienced by the majority of citizens on a day-to-day basis) consists primarily of state law, which can and does vary greatly from one state to the next. 
American law has diverged greatly from its English ancestors both in terms of substance and procedure. In the United States, the law is derived from five sources: constitutional law, statutory law, treaties, administrative regulations, and common law (which includes case law). Where Congress enacts a statute that conflicts with the Constitution, state or federal courts may rule that law to be unconstitutional and declare it invalid.
“In the public debates regarding the ratification of the proposed constitution, a principal concern emerged: the proposed constitution contained no explicit protection of individual rights. The framers of the Constitution assured the public in those states where this debate was most intense that, once adopted, the Constitution would be amended to include individual rights. That concern prompted the proposal of 12 constitutional amendments in the same year that the Constitution went into effect. Ten of these amendments passed, and they later became known as the Bill of Rights. In addition to the amendments contained in the Bill of Rights, the US has amended the Constitution 17 more times.”
Other Jurisdictions that follow the Common Law System are as follows:
- United Kingdom except Scotland
- United States except Louisiana
- Former British colony and/or Commonwealth territories/countries, including India except Goa, Australia, New Zealand, Singapore, and Canada except Quebec
Examples of jurisdictions that use the civil law system include the following:
- Most European Union (EU) nations, including Germany and France where civil law was derived, but not the United Kingdom, Ireland, or Cyprus
- Most of continental Latin America except Guyana and Belize
 Introduction to the American Legal System | LexisNexis  What is the Civil Law? | LSU Law – Civil Law Online  Ibid.  Ibid 2.  Ibid.  Legal Systems in the United States: Overview | Practical Law (thomsonreuters.com)  Introduction to the American Legal System | LexisNexis  Ibid.  Ex parte Virginia, 100 U.S. 339 (1880).  Head Money Cases, 112 U.S. 580 (1884).  Skidmore v. Swift & Co., 323 U.S. 134 (1944).  Cooper v. Aaron, 358 U.S. 1 (1958).  William Burnham, Introduction to the Law and Legal System of the United States, 4th ed. (St. Paul, MN: Thomson West, 2006), 41.  Gregory v. Ashcroft, 501 U.S. 452 (1991).  Kowalski, Tonya (2009). "The Forgotten Sovereigns". Fla. St. U. L. Rev. 36 (4): 765–826.  United States v. Lopez, 514 U.S. 549 (1995).  Pruneyard Shopping Center v. Robins, 447 U.S. 74 (1980).  California v. Ramos, 463 U.S. 992 (1983).  Hughes, Graham (1996). "Common Law Systems". In Morrison, Alan B. (ed.). Fundamentals of American Law. Oxford: Oxford University Press. pp. 9–26. ISBN 9780198764052.  Friedman, Lawrence M. (2019). A History of American Law (4th ed.). Oxford: Oxford University Press. p. 646. ISBN 9780190070915.  White, G. Edward (2012). Law in American History, Volume 1: From the Colonial Years Through the Civil War. Oxford: Oxford University Press. pp. 49–50. ISBN 9780195102475.  Paul Bergman and Sara J. Berman-Barrett, Represent Yourself in Court: How to Prepare & Try a Winning Case, 6th ed. (Berkeley: Nolo, 2008), 481.  See Marbury v. Madison, 5 U.S. (Cranch 1) 137 (1803).  Id 6.  Chapter 2.pdf (americanbar.org)  Ibid.