The peculiarity of the US legal system was the fact that it was a combination of the federal legal system and the legal systems of the states, which, for all their uniqueness and independence, had an internal unity.
The formation of the U.S. legal system began as early as the colonial period. All 13 colonies, despite differences in social and political structure, had common legal roots. During the seventeenth and eighteenth centuries, there was an active absorption of English “common law,” “equity law” and statutory law, which had direct effect in the colonies. But this absorption was not of a mechanical nature; it simplified and adapted the rules to the needs of colonial society.
After independence the influence of English law began to wane somewhat. In a number of states (e.g., New York and Maryland) the application of English law, originating after 1776, was prohibited. In some states even the citation of new decisions of the courts of the former metropolis was forbidden. In the early nineteenth century, however, the authority of English “common law” increased. In 1804 the states of New York and Massachusetts began to officially publish court decisions, and this practice was followed by other states. By 1880 about 4,000 volumes of federal and state court decisions had been published. The system of “common law” was also adopted by the newly formed states. However, American “common law” was not an exact copy of the English system. In the U.S. there was a much earlier fusion of “common law” and “the law of equity. The principle of judicial precedent obliged courts to follow the decisions of higher courts, but the courts did not consider themselves bound by their own decisions. The supreme authority in matters of law was the U.S. Supreme Court, whose interpretations became binding on all courts.
In addition to the common law system, a written, or statutory, law developed in the U.S., with constitutions and federal and state legislation based on them as its main source. Beginning in 1828, first New York State and then others began to publish official collections of legislation.
The question of whether or not there was a federal “common law” in the United States became a serious legal problem. The 1789 Act provided that federal courts could apply, in matters not governed by federal law, the laws of the state where the federal court heard the case. However, it remained unclear whether the jurisprudence of that state could be used. There were differing views and conflicting jurisprudence. In 1842, in Swift v. Tison, the court for the first time applied the “common law of the land” doctrine. However, the application of this principle began to lead to an unjustifiable duality of decisions. Ultimately, the notion of “federal common law” was held to be contrary to the spirit of the Constitution, since it enshrined the primacy of the federal government in those matters which the Constitution referred to state authority.