In 2011, the Vienna Convention on Diplomatic Relations (VCDR) celebrated its 50th anniversary since the United Nations Conference on Diplomatic Immunities and Privileges in 1961. During that time VCDR became the source of references to the scope of diplomatic privileges and immunities conferred on diplomats and their families. By exploring the theoretical basis of diplomatic privileges and immunities, including the absolute inviolability of diplomatic immunity, the paper explores links between diplomatic theory and practice. Diplomatic privileges and immunities are largely codified in the 1961 Vienna Convention on Diplomatic Relations (VCDR). The analysis of the background of the VCDR negotiations of 1961 shows that, although diplomatic powers have a clear theoretical basis, the theory is secondary during the negotiation process. Basically based on functional necessity, and partly on the theory of representative character, the theoretical approach was consistently applied during the convention.