3. Citizens of the parties to the dispute cannot be heard by a group of technical experts without the common agreement of the parties to the dispute, unless the panel considers that the need for scientific expertise cannot be met by other means. Government officials of the parties to the dispute are not allowed to sit in a panel of technical experts. Members of technical expert groups perform their individual duties and are not representatives of the government or representatives of an organization. Governments or organizations therefore do not instruct them on the issues in front of a group of technical experts. 15.5 The annexes to this agreement are an integral part of this agreement. The CTA ensures that technical regulations, standards, testing and certification procedures do not create unnecessary trade barriers. The agreement prohibits technical requirements that are created to restrict trade, contrary to technical requirements created for legitimate purposes, such as consumer or environmental protection.  Its objective is to avoid unnecessary barriers to international trade and to recognize all WTO members in order to protect legitimate interests on the basis of their regulatory autonomy, although they encourage the application of international standards. The list of legitimate interests that may justify a trade restriction is not exhaustive and covers the protection of the environment, health and safety of people and animals.  In accordance with Article 1, this agreement applies to all industrial and agricultural products, with the exception of services, health and plant health measures (as defined in the agreement on the application of sanitary and plant health measures) and “purchase specifications established by public authorities for the production or consumption needs of public administrations” (Article 1.4).  10.7 When a member has reached an agreement with another country or country on issues relating to technical regulations, standards or compliance assessment procedures that could have a significant impact on trade, at least one member of the agreement informs the other members, through the secretariat, of the food products that must be covered by the agreement and a brief description of the agreement.