The article considers the place, role and limits of use of evaluation concepts in legal reasoning. In this context the notion of legal reasoning has been defined, the main definitions of evaluation concepts accepted in logic and jurisprudence have been reviewed. The features of evaluation concepts have been identified. Evaluation concepts have an open logical structure, offer some latitude to the enforcer in legal interpretation, give legal reasoning flexibility and dynamism. The attributes of evaluation concepts such as subjective nature have been noted, this property often communicates ambiguity and vagueness to legal rules. Therefore, the use of evaluation concepts in legal reasoning is a process requiring particular professionalism. Some ways have been suggested to help to use correctly evaluation concepts in legal reasoning. They include reliance on common values, identification of formal concepts to which the evaluation concept relates, developing a logical culture among law enforcement professionals, raising the general level of legal awareness.