A lawyer, similar to any user of the language for specific purposes, uses a legal language. Jargon lexicon of criminal layers (so-called criminonyms) is not characteristic of the lawyer. However, sometimes it is an inseparable part of the language used by a certain “caste”. It may be stated that the jargon is a secret code of mutual communication for closed social layers, riddles of their speech that try to mask and separate from other social layers, especially from “strangers” – wardens, investigators, etc. The lawyer sometimes has to decode that jargon and to understand the meanings of the words used in the jargon. There is no Lithuanian jargon dictionary yet. Therefore, the article analyses examples from the Great Jargon Dictionary of the Russian Language and The Russian Slang Dictionary. Jargon lexicon is discussed in the article in detail. However, the author states that the analysed jargon lexicon is used in speeches of court orators very rarely and is justified only when it has a motivated purpose: helps to present authentic words of another person; to individualize and epitomize the accused or a witness; to show the social environment which he/she is from; to rally or to evaluate critically; to arouse pity or sympathy. Those cases when the ambiguous speaking using paronyms and homonyms harms the style, when similarly or identically sounding words are confused
