Historyof Law Kyiv Rus, without regard to the more than 200-years-old period of her research, continues to remain in the field of attention of scientists, and, also, politicians. One of important questions of History of Law these period is a question about rule-making and role in him shows of witnesses. This problem was studied thoroughly enough as early as ХІХ of century and one of active acting persons of discussion round this theme there was a historian of law, native of Ukraine, professor of the Kyiv university Vasyl Hryhorovych Demchenko. In the master's degree dissertation "Historical research is about the shows of witnesses as proof in matters of judicial, accoding the Russian law before Peter the Great" (in 1859), V.H. Demchenko considered becoming of such important institute of judicial law as institute of certificate in detail. A scientist marks the value of judicial proofs in general genesis of law, he underlines that before an arbitrariness was the only means of guard of rights, but development of society resulted in a volume, that next to this means already the guard of rights for cramps began to be used. He considered that the judicial aspects related to the shows of witnesses are system enough set forth in Russian True. A researcher paid attention to that Russian True talks about witnesses in most cases in connection with those the offences that must be by them validified, in accordance with every case, where this proof is required. Therefore resolutions about them matter general not rules that spread to all possible cases of their use, but touch only private, that have force only for those cases for that they are straight set. General rules some resolutions that is unconnected with determinations about separate offences matter only. A scientist underlined that the judicial role of witnesses accoding Russian True did not have been limited to only the value of them, as judicial proof. On occasion they got the certain participating in realization of process. It touched those judicial events application of that got to parties without every participation of some government bodies ( for example,zvid). In the research of V.H. Demchenko analysed a question about the capacity of witnesses for a certificate, specified also on space of application of proofs with participation of witnesses after Russian True, order of finishing telling with participation of witnesses, force of shows of witnesses. Thus, V.H. Demchenko no doubt, was one of the most skilled specialists on history law that investigated time of Kyiv Rus.