“It has long been a black letter law that the personal service in its geographical area establishes the personal jurisdiction of a court over the defendant.” The term certainly refers to a distillation of the common law into general and recognized legal principles. This is evident in the Supreme Court quote above, where the court notes that while the Black Letter Act is clear, the New York precedent deviates from general principles. The law of black letters condenses the abundant jurisprudence of common law societies into reusable rules. As a general rule, these rules can be applied to any relevant set of facts to achieve a consistent result. For example, the Black Letters Act may include the standard elements of a contract (offer, acceptance, and performance) or the technical definition of murder (the unlawful killing of a malicious person). Among the legal disciplines that rely most on black letter law are contract law, tort law, and property law. The concept of black letter law was born from the practice of writing law books and writing legal precedents in Gothic black letters. It was a tradition that survived conversion to Latin and italic text for all other printed works. English law retained the bold black Gothic font because it symbolized the law of England itself. It was not until the mid-nineteenth century that the legal profession began to use Roman letters. This was not just a change of mode, but rather an attempt to improve access to the law for the average person.
A century later, in an era of increasing diversity, blurred boundaries and changing social values, the application of the black letter approach to legal analysis is still the subject of debate. A precise knowledge of black letter law is essential, at least for the success of future lawyers, as they form the basis of a much more complex and critical legal analysis framework. In an 1831 case before the U.S. Supreme Court, Jackson ex dem. Bradstreet vs Huntington`s disease, the phrase “black letter” has been used: “It is rare that a case in our time appreciates so much of the black letter; but the course of decisions in New York makes it inevitable… ».  The term “law of the black letter” was used in Naglee v. Ingersoll, at p. 7. 185 (1847). The term does not come from the connection to Black`s Law Dictionary, which was first published in 1891. Instead, it probably refers to the practice of writing legal books and citing legal precedents in black letters, a tradition that survived long after the switch to Roman and Italic texts for other printed works. A legal system that is not based, at least in part, on a black-letter approach reduces citizens` ability to predict the outcome of a process and whether their actions are within the limits of legality.
The law of the black letter refers to the concept that rules are generally known and free from doubt or challenge. More than 100 years ago, two of the most respected men in common law history predicted a break with the Black Letter Act. Oliver Wendell Holmes, Jr. explained: “For the rational study of the law, the man with black letters [i.e. Master of Jurisprudence, as it is written] may be the man of the present, but the man of the future is the man of statistics. Justice Learned Hand upheld Holmes` assertion, stating, “It is equally important for a judge who is asked to answer a question of […] Law, at least a reclining knowledge of Acton and Maitland, Thucydides, Gibbon and Carlyle, Homer, Dante, Shakespeare and Milton, Machiavelli, Montaigne and Rabelais, Plato, bacon, Hume and Kant, as books written specifically on this subject. “In common law jurisdictions, black-letter laws are the established rules of law that are no longer the subject of reasonable litigation.  Some examples are the “Black Letter Act”, which must take into account the conclusion of a contract, or the “Black Letter Act”, according to which the registration of a trademark requires an established use in the course of business.
Black letter law can be compared to legal theory or unresolved legal issues. .