The subject of the thesis is the witness as one of the means of evidence within the litigation and the specifics of his role. In the introduction the term is defined, the subject of the testimony is analyzed and the foundations of the distinction in relation to other means of evidence are laid. The duties of witnesses are interpreted through their content, the ability of the parties to testify and the overall admissibility of testimony. After listing the advantages and the disadvantages of the title institute, there follows a chapter on prohibitions of testimony, in which the emphasis is on the impediments which come in the forms of official and military secrets and the way they affect the testimony. The possibility of withholding testimony is further elaborated, first through the chapter on general denial and then through the chapter on denial of answers to individual questions, concluding the entire analysis with a special chapter on evaluating the justification of the reasons for both variants. Next is the hearing, where the procedure itself is processed through the element such as the method of hearing, the warnings that precede it, the general questions that are asked, the confrontation of the opposing parties, some of the possible flaws that the persons invited to testify might have, concluding with the concept of a sworn statement. The following is a chapter on sanctions that affect a orderly invited witness in case he unjustifiably violates the duty to attend, and which occur in the forms of forced attendance, fines, imprisonment or indemnity. The thesis is concluded with the witness's right to compensation for the costs that the civil duty to testify causes him.