This article concerns the most influential Western theories of legalargumentation developed by Chaïm Perelman, Stephen Toulmіn, Robert Alexy, DouglasWalton, Frans van Eemeren, Rob Grootendorst and their students. These moderntheories of argumentation recognize as quite acceptable arguments ad hominem, whichin traditional logic are considered as non-admissible. Recognition of correctness ofarguments ad hominem requires multifactorial approach in argumentation theory, whichin addition to purely logical and purely legal analysis includes philosophical, psychological,moral dimensions of argumentation.