(a) arising out of a contract concluded by a consular officer or a consular employee in which he did not contract expressly or impliedly as an agent of the sending State; or (b) by a third party for damage arising from an accident in the receiving State caused by a vehicle, vessel or aircraft. Article 44 Liability to give evidence 1. Members of a consular post may be called upon to attend as witnesses in the course of judicial or administrative proceedings. A consular employee or a member of the service staff shall not, except in the cases mentioned in paragraph 3 of this article, decline to give evidence. If a consular officer should decline to do so, no coercive measure or penalty may be applied to him. 2. The authority requiring the evidence of a consular officer shall avoid interference with the performance of his functions. It may, when possible, take such evidence at his residence or at the consular post or accept a statement from him in writing. 3. Members of a consular post are under no obligation to give evidence concerning matters connected with the exercise of their functions or to produce official correspondence and documents relating thereto. They are also entitled to decline to give evidence as expert witnesses with regard to the law of the sending State. Article 45 Waiver of privileges and immunities 1. The sending State may waive, with regard to a member of the consular post, any of the privileges and immunities provided for in articles 41, 43 and 44. 2. The waiver shall in all cases be express, except as provided in paragraph 3 of this article, and shall be communicated to the receiving State in writing. 3. The initiation of proceedings by a consular officer or a consular employee in a matter where he might enjoy immunity from jurisdiction under article 43 shall preclude him from invoking immunity from jurisdiction in respect of any counterclaim directly connected with the principal claim. 4. The waiver of immunity from jurisdiction for the purposes of civil or administrative proceedings shall not be deemed to imply the waiver of immunity from the measures of execution resulting from the judicial decision; in respect of such measures, a separate waiver shall be necessary. 18