A “thief in law” (Russian: вор в зако́не, Georgian: კანონიერი ქურდი), in the Soviet Union, the post-Soviet states, and respective diasporas abroad is a specifically granted formal and special status of "criminal authority" (Russian: криминальный авторитет, romanized: kriminalny avtoritet), a professional criminal who enjoys an elite position among other notified mobsters within the organized crime and correctional facility environments and employs informal authority over its lower-status members.

The phrase "Thieves in Law", otherwise known as "Vory", is a calque of the Russian slang phrase "вор в зако́не," literally translated as "a Thief in [a position of] the law." The phrase has two distinct meanings in Russian: "A legalized thief" and "A thief who is the Law." "Vor" came to mean 'thief' no earlier than in the 18th century, before which it meant "criminal". The word retains this meaning in the professional criminal argot

Each new Vor (thief) is a made and vetted, literally "crowned" male; with respective rituals and tattoos, by the consensus of several Vory. Vor culture is inseparable from prison organized crime: only repeatedly jailed convicts are eligible for Vor status. Thieves in law are drawn from many nationalities from a number of post-Soviet states, but the majority are ethnic Georgians and ethnic minorities from Georgia.