Environmental management systems (EMS) are management instruments that should establish policies, responsibilities, and procedures relating to environmental issues. EMS are expected to enable continuous improvement in terms of environmental performance. EMS are usually based on accepted standards, such as ISO 14001. More technically, the International Standardization Organization (ISO) defines an EMS as part of the management system (MS)of an organization that is utilized to manage environmental aspects, to fulfil compliance obligations and legitimate stakeholder expectations, and address risks and opportunities (ISO 14001, § 3.1.1.). Organizations that implement an EMS on ISO 14001 need to accordingly comply with the requirements which have been laid down in the standard. A third-party certification usually demonstrates compliance with ISO 14001, although self-declarations or conformance declarations by customers or other external interested parties are possible (ISO.