Close attention to speech behavior in the sphere of professional communication presupposes noticeable interest in individual and social aspects of a speaker’s conduct in the field of legal activities. In the present article the authors treat contact establishing tactics as an inalienable part of emotional influence strategy in Russian, Kazakh and American trial discourse. It should be mentioned that the influence of ethnic and cultural factors on differences of speech behavior of professional participants of Russian, Kazakh and American trial discourses has not been studied thoroughly enough yet. The present research is characterized by a wish to identify the dependency of speech behavior on trial discourse professional participants (the choice of communicative tactics within basic communicative strategies) of their social roles, as well as on the peculiarities of ethnic mentality of the treated linguistic cultures’ representatives. While conducting the research the achievements of Linguistic Conflict Study, Social Linguistics, Interpretation Theory, Speech Acts Theory, as well as Jurisprudence, Communication Study and Cognition Science have been integrated. Within the frames of a complex approach to the study of trial communication there were singled out and described earlier not systematized in the Theory of the Language from comparative angle tactics of communicative influence of trial discourse’ professional participants (prosecutors and defense lawyers) of Russian, Kazakh and American linguistic cultures; there were defined linguistic, stylistic and rhetorical devices and means constituting them, ethnic and cultural specificity of speech behavior of the representatives of the taken linguistic cultures in the field of trial communication was also detected. The following methods of research were used: hypothetical and inductive, descriptive, introspective, interpretative, contextual and functional comparative quantitative and qualitative analysis, linguistic patterns’ analysis. Among the main results and inferences the following ones should be mentioned: 1. Variability and flexibility in building up communicative strategies is achieved by means of a definite set of communicative tactics, the choice of which is predetermined by communicative intentions and communicative situation. 2. Ethnic and cultural peculiarities of trial discourse can be defined in the course of the analysis of the set and frequency of the use of communicative tactics within realization of basic communicative strategies by its participants. Contact establishing tactics within the frames of emotional influence strategy in particular are differentiated by a number of isomorphic and allomorphic features in the studied linguistic cultures, which is illustrated in the article. The accuracy of the results is confirmed by the volume of chosen for analysis patterns as well as profound analysis of the data. The research data is represented by trial notes of attorneys for defense and prosecution speeches at 17 trials in Russian, Kazakh and American courts, the data refers to the period of 1995-2012.