Theories of Diplomatic Immunity
Since the 16th century there have been three major theories of diplomatic immunity. Each theory plays a prominent role during different periods in history. These theories are: (a) personal representation, (b) extra territoriality and (c) functional necessity. Not only will their historical context be reflected but reference to their use in modern practice will be made in this study to indicate the role of each theory throughout the ages and how they apply today.
- Personal Representation
This theory has the deepest and earliest origin. Long before the age of the modern diplomats and resident embassies there were rulers who sent representatives. The theory gained widespread recognition during the Renaissance period when diplomacy was dynastically oriented. These representatives received special treatment. When the receiving State honoured them their ruler was pleased and unnecessary conflict was avoided. The representative was treated as though the sovereign of that country was conducting the negotiations, making alliances or refusing requests. Montesquieu describes representation as “the voice of the prince who sends them, and this voice ought to be free, no obstacle should hinder the execution of their office: they may frequently offend, because they speak for a man entirely independent; they might be wrongfully accused, if they were liable to be punished for crimes; if they could be arrested for debts, these might be forged.” Ross discredits this theory on three grounds. First, the foreign envoys cannot have the same degree of immunity as the ruler or sovereign. Second, the decline of the monarchs and the progression of majority vote make it unclear who the diplomat represents. Last, the immunity does not extend from the consequences of the representatives’ private actions.
- Extra territoriality
This theory was of limited applicability in the early centuries after the establishment of resident embassies in the 15th century. It derived from imperfect notions of personal and territorial court held that by regarding the ambassador as the sovereign’s representative, it ensured their stature. If they were not accorded exemptions, every sovereign would cast a shadow on his own dignity when sending an ambassador to a foreign State. If applied in modern times this theory would be less Jurisdiction. During this time there was a great emphasis over the supremacy of national law on everyone in the territorial state, irrespective of their nationality. In order to try and avoid this being imposed on diplomats, the theory of extra territoriality was developed. This is based on the Roman law principle whereby a man took his own land’s law with him when he went to another land. The crux of this theory is that the offices and homes of diplomats and even their persons were to be treated, throughout their stay, as though they were on the territory of the sending State and not that of the receiving State. The irony of this theory is that a diplomat would not necessarily be immune for the same illegal conduct in the sending State, but could not be prosecuted for it. Further, ambassadors were seen in two ways, (a) as a personification of those who sent them, and (b) they were held to be outside the limits of the receiving State.
(c) Functional Necessity
This theory is more dynamic and adaptable than the other two theories and has gained acceptance since the 16th century to modern practice. The rationale behind a need for a diplomat’s privilege and immunities is that it is necessary for him to perform his diplomatic function. Diplomats need to be able to move freely and not be obstructed by the receiving State. They must be able to observe and report with confidence in the receiving State without the fear of being reprimanded. This theory gained credence during the First World War and gained even more impetus since then due to the expansion of permanent resident embassies, the increase of non-diplomatic staff to help perform diplomatic functions, and the increase of international organisations which require immunity to be granted to more people. So it seems that necessity and the security to perform diplomatic functions are the real reasons for diplomatic immunity; hence the test is not whether acts are public, private or professional, but whether the exercise of jurisdiction over the agent would interfere with his functions. Functional necessity is recognised in the Vienna Convention, and was deemed practical under the UN Convention.
References and Works Cited
 R. A. Wilson, Diplomatic Immunity from Criminal Jurisdiction: Essential to Effective International Relations, International & Comparative Law Journal.Vol. 7,at 2 (1984).
 F. Przetacznik, The History of the Jurisdictional Immunity of the Diplomatic Agents in English Law, Anglo-American Law Review, Vol.355,at 448, (1978).
 Ross, Supra Note 3, at 177-178.