Diplomatic immunity is contained in Article 31 of the Vienna Convention which states –
A diplomatic agent shall enjoy immunity from the criminal jurisdiction of the receiving States. He shall also enjoy immunity from its civil and administrative jurisdiction except in the case of:
(a) a real action relating to private immovable property situated in the territory of the receiving State, unless he holds it on behalf of the sending State for the purposes of the mission;
(b) an action relating to succession in which the diplomatic agent is involved as executor, administrator, heir or legatee as a private person and not on behalf of the sending State;
(c) an action relating to any professional or commercial activity exercised by the diplomatic agent in the receiving State outside his official functions.
A diplomat thus enjoys immunity from all criminal activities and cannot be tried in the jurisdiction of the receiving state. He is also immune from civil jurisdiction with the above 3 exceptions. However, the diplomat is always liable to the jurisdiction of the sending state and thus even though he may not be tried in a foreign court for criminal / civil acts, he can be tried for the same acts in the domestic courts.