(4)Member States may decide to accept joint inspections in exceptional circumstances where this is necessary to ensure effective supervision. Member States may allow that cooperation with the competent authorities of the United States of America takes place under the form of joint inspections or through observers without inspection or investigation powers and without access to the confidential audit working papers or to other documents held by statutory auditors or audit firms. Such cooperation should always take place under the conditions set out in Article 47(2) of Directive 2006/43/EC and in this Decision, in particular as regards the need to respect sovereignty, confidentiality and reciprocity. Member States should ensure that any joint inspections carried out in the Union by their competent authorities and the competent authorities of the United States of America under Article 47 of Directive 2006/43/EC should be under the leadership of the competent authority of the Member State concerned.