The surviving fragments show that it was not a legal code in the modern sense of the term. It did not contain a complete and coherent system of all applicable rules, nor legal solutions for all possible cases. On the contrary, the tables contain specific provisions modifying customary law existing at the time. Although the provisions cover all areas of law, most of them are devoted to private law and civil procedure. All civilizations had laws. But from 451 BC. A.D. to 450 B.C. The Romans made great strides in structuring a legal system codified with the 12 tablets.

This was the basis of the statutes of our legal system. In the mid-16th century, rediscovered Roman law dominated the legal practice of many European countries. A legal system had emerged in which Roman law blended with elements of canon law and Germanic custom, especially feudal law. This legal system, which was common throughout continental Europe (and Scotland), was called the Ius Commune. This ius commune and the legal systems derived from it are commonly referred to as civil law in English-speaking countries. As the Roman Republic became an empire, its rulers faced the growing challenge of governing an increasingly diverse and dispersed population. Legal problems and disputes arose not only between Roman citizens, but also with non-citizens who lived or traveled in their territories to whom ius civile did not apply. This led to the development of ius gentium (“law of nations”), which was the set of laws applicable to all human beings and based on common principles and considerations shared by civilized societies and humanity, and ius naturale (“natural law”), a category of law based on principles shared by all living beings. Humans and animals (for example, laws on reproduction or physical defense against attack). As the law became more complex, Roman rulers needed a larger group of legal authorities to organize the system of legal formulas and decisions.

In the second half of the third century BC. A.D., a new professional group of legally trained specialists, lawyers, emerged to meet this demand. Lawyers were not involved in the administration of justice, but focused on interpreting and preparing formal opinions on the law. It was the scholarly works and writings of generations of great jurists that elevated Roman law to its peak during the first two and a half centuries AD, the so-called classical period of Roman law. There was at least one part of the Roman Empire that did not want to pass these laws – the island of Great Britain, but otherwise most of Western Europe adopted the Roman legal system. These laws, created by the Romans, are known as Roman law and civil law. The success of the Roman legal system and the Latin legal terminology that accompanied it was so great that it went on to form the basis of law in most English-speaking countries. It would also be incorporated in many jurisdictions in the United States.

Although ancient Roman law is not strictly enforced worldwide, many legal systems in modern times are based on ancient Roman codes, Roman laws, and traditions. In this way, many aspects of Roman law were incorporated into more coherent legal systems and are still expressed in the language of the courts today. Today, a good knowledge of Roman law during the Roman Empire is fundamental to understanding the legal systems that exist in the present. For many law students, the study of ancient Roman law is mandatory to help them gain a comprehensive knowledge and understanding of civil law and its jurisdictions. Around 300 BC. The Roman jurist and politician Gnaeus Flavius published the rules of legal procedure that had not been accessible to the plebeian class until then. Until now, it seems that these were only accessible to certain priests (pontificates) or patricians (aristocrats). With his publication of Jus Flavianum, Flavius popularized the law. One of the most eminent jurists was Quintus Mucius Scaevola, who wrote many treatises on a wide range of aspects of Roman law. By the time of the Principate in 27 BC, Rome had developed a very comprehensive legal system, which also produced a refined legal culture when the ancient Roman Republic was replaced. After some resistance from the patricians, a committee produced 12 bronze tablets, which together contained the first law of Rome. This code, called the Twelve Tables, contained important legal concepts such as: The adaptation of the law to new needs was entrusted to legal practice, judges and, in particular, lenders.

A praetor was not a legislator and technically did not create a new law when he issued his edicts (magistratuum edicta). In fact, the results of its judgments enjoyed legal protection (actionem dare) and were often the source of new laws. The successor of a praetor was not bound by the edicts of his predecessor; However, he adopted rules drawn from the edicts of his predecessor that had proved useful. In this way, a constant content was created, which went from edict to edict (Edictum traslatitium). After the dissolution of the Western Roman Empire, Roman law remained in force in the Eastern Roman Empire. From the 7th century, the legal language in the East was Greek. The praetors were appointed for one year and became increasingly powerful judicial officials. At the beginning of their mandate, they began by making a written declaration, known as a praetorian edict. This edict described the rights that the praetor wanted to enforce and the remedies he would recommend in case of illegal acts. Eventually, the edict became a standard set of legal principles and rules passed from one praetor to another. The praetors used their edicts to interpret the Twelve Tablets as well as the laws passed by the assemblies of the Republic.

In the Western world, only England, its colonies and the Scandinavian countries developed legal systems different from those of ancient Rome. But even these countries owe a debt of gratitude to the Romans for creating many legal concepts, principles, and rights that govern the lives of their citizens today. The lawyers performed various functions: they prepared legal opinions at the request of private parties. They advised judges in charge of the administration of justice, especially praetors. They assisted the praetors in drafting their edicts in which they publicly announced, at the beginning of their mandate, how they would exercise their functions and the formulas according to which certain procedures were conducted. Some lawyers have also held high judicial and administrative positions themselves. Students who learned Roman law in Bologna (and later in many other places) found that many rules of Roman law were better suited to regulating complex economic transactions than the usual rules that applied throughout Europe. For this reason, Roman law, or at least some provisions borrowed from it, was reintroduced into legal practice centuries after the end of the Roman Empire. This process was actively supported by many kings and princes who employed university-trained jurists as advisors and court officials, trying to benefit from rules such as the famous Princeps legibus solutus est (“The ruler is not bound by the laws”, a term originally coined by Ulpian, a Roman jurist). The Justinian Codex and the institutes of Justinian were known in Western Europe and, together with the earlier codex of Theodosius II, served as a model for some Germanic legal systems; However, the digestible part was largely ignored for several centuries until a manuscript of the digests was rediscovered in Italy around 1070.