The American common law developed very differently while in use with colonial and state governments, and the Federal courts made decisions upon Federal codified statutory laws. The American common law originated in parts from English common law principles, American colonial and state case law and principles, American interpretations of natural law philosophy, principles of international law, and more. While English common law was an important founding influence upon American common law, the American judiciary and legislatures abandoned, abrogated, and supplanted most of what little was known to the Americans in an age where little more than the summaries of the principles were available in print to the American colonists and Constitutional Convention.
Using their personal experience with the English, Dutch, French, German, Roman, and other legal systems from the American colonies, Europe, and other European colonies, the Americans made a new common law unique in many aspects. It was only later in the mid to late 19th Century that published volumes of common law decisions became widely avaiable enough for jurists to make routine comparisons of the case law of the American courts to the case law of the foreign courts of England and elsewhere.