This article considers the belonging of speech means to linguistic categories when performing linguistic expertise on terrorism materials (responsibility for which is provided by article 205.2 of the Russian Criminal Code) in order to consolidate in science the dominant approach to this issue, as well as to improve the effectiveness of the expert linguist work. The article introduces the concepts of "legal component", "linguistic component", proposed for consideration within the framework of forensic linguistics. The article contains the results of the analysis of the review of the existing scientific approaches to the definition of modality, the correlation between modality and evaluation, to the methodological side of the problem of searching for linguistic components in the text, as well as the result of the analysis of the review of articles related to linguistic expertise (including materials of terrorist/extremist slant) over the past ten years. The research part of the article correlates the "legal components" recorded in Article 205.2 and the "linguistic components" reflecting the category reference of the meaning. The article also provides a set of questions that are posed for linguistic forensic examination. Besides, the article contains the list of methods of linguistic analysis necessary for application in search of means of expression of modality, examples of means of expression of the discussed types of modality are given. The article also outlines the prospect of developing a detailed algorithm for analysing the most frequently encountered objects of linguistic expertise using these methods.