1. The immunity from jurisdiction of diplomatic agents and of persons enjoying immunity under article 37 may be waived by the sending State.
2. Waiver must always be express.
3. The initiation of proceedings by a diplomatic agent or by a person enjoying immunity from jurisdiction under article 37 shall preclude him from invoking immunity from jurisdiction in respect of any counter-claim directly concerned with the principal claim.
4. Waiver of immunity from jurisdiction in respect of civil or administrative proceedings shall not be held to imply waiver of immunity in respect of the execution of the judgment, for which a separate waiver shall be necessary.