The article is devoted to highlighting domestic experience and foreign practice of legal argumentation in court proceedings. The Great Legal Encyclopedia defines legal argumentation as the process of giving arguments legal meaning and establishing relationships between them, which acquires jurisprudence. forms when harmonizing logical rules with legal norms.
 It is stated that legal reasoning in court decisions is mandatory, since the acceptability of legal decision- making depends on the procedures of argumentation and the desire to achieve the truth in law. Therefore, the justice of court decisions is determined by their compliance with the requirements of legality, reasonableness and motivation.
 It is established that an argument is a statement containing premises and a conclusion, not all of which are expressed in real arguments. In legal argumentation, evidence is an auxiliary tool of argument.
 In practical discourse, in order to achieve the criteria of rationality and correctness, there is often a need to apply special knowledge, the bearers of which are experts. Opinions of experts provided within the limits of the examination appointed by the court are sources of evidence.
 Evidence must be proper, admissible, reliable, sufficient. That is why forensic experts involved in the judicial process must possess the skills of argumentation and oral communication, be professional, authoritative, and their conclusions substantiated and impartial. That is, the rules of legal discourse and the principles of legal argumentation necessarily apply to the judicial expert, who appears as one of the subjects of argumentation.
 It was found that domestic courts do not always trust the conclusions provided by experts. The results of a psychophysiological diagnosis of a person using a polygraph do not provide advantages in proof, but «are taken into account, along with other evidence».
 Involvement of experts in the legal process does not always provide grounds to include the conclusions they provide in the evidence base, let alone consider them as real arguments. There is a need for legislative regulation of the issue of the possibility of the participation of a polygraph specialist in the legal process.
 The evidence practice was outlined and the role of expert witnesses in Italy was clarified. Thus, in Italian civil proceedings there are two types of experts: the judicial technical expert appointed by the judge (CTU) and the expert appointed by the parties (CTP). The expert should not have any interests related to the proceedings. The appointed expert must agree to his own appointment and can reject it only for valid reasons assessed by the judge.
Read full abstract