What international convention covers the functions of a diplomatic mission, including the right to gather information by lawful means?

💡 Explanation:

The Vienna Convention on Diplomatic Relations (VCDR) of 1961 is the cornerstone of diplomatic law. Article 3, which defines the functions of a diplomatic mission, includes 'ascertaining by all lawful means conditions and developments in the receiving State, and reporting thereon to the Government of the sending State.' Lawful observation of public court hearings is generally considered to fall under this function.