One of the purposes of the article is to provide an up-to-date account for the Roman maxim jura novit curia (the court knows the law). Traditionally jura novit curia means that the court alone is responsible for determining which law applies to a particular case, and how without being limited to the legal arguments advanced by the parties. On the basis of the systematic investigation of different elements of legal technology (legal fictions, principles, axioms or presumptions) the author formulates the conclusion that jura novit curia can be attributed to the general legal presumption, which is related to the characterization of law enforcement activities of state bodies. Moreover, taking into account the interconnection of presumptions and principles of law, the author indicate that there is a corresponding functional principle of legality to the presumption jura novit curia. In the second part of the article the author criticizes scientific assessment of the presumption of jura novit curia as confirmation of position on the exclusion of legal knowledge from the scope of special ones. It was argued in favor of legitimation of the legal advices on interpretation and permissible application of law in order to increase the degree of probability of the presumption of jura novit curia. Other substantial elements of the presumption of jura novit curia, namely, an initiative and independent study of the rules of law by the court without being limited to the legal arguments advanced by the parties do not conflict with the possibility of a court to get legal advices from specialists who do not intervene the competence of the judge making the final decision. In the third part of the article, the author finds the arguments for exclusion maxim jura novit curia form foreign laws are not conclusive. It may be suggested that this assumption can lead to the negative consequences that can be expressed in the unreasonable restriction of the application of foreign law. On the basis of the analysis it is possible to indicate that jura aliena novit curia is the branch presumption of the international civil process, which correlates with the content of the principle of legality and the principle of the international civil process - the establishment of the content of foreign law ex officio. The author reasons that ignoring presumption of jura aliena novit curia obviously leads to difficulties for the principle of applying foreign law ex officio, since it is impossible to apply foreign norms based on presumption jura non aliena novit curia. The presumption of jura aliena novit curia should cover not only the content of foreign law, but also several conditions for its application based on national law. The article challenged the theory that the requirement to apply foreign law in the same way as it is applied abroad is the fiction. The author justified that the notion of "foreign law" can be attributed to the fictions taking into account that the court can apply only private foreign law and some foreign procedural rules with considering national law restrictions.
