According to ISO 9001:2015, clause 7.2, an auditor shall have the competence to:

Understand the requirements of ISO 9001 and how they relate to the audit

Understand the organization’s quality management system and its processes

Understand the applicable legal, regulatory, contractual and other requirements that affect the audit

Understand the needs and expectations of interested parties other than customers

Plan and conduct audits in accordance with ISO 19011

Evaluate audit evidence and draw appropriate conclusions

Communicate audit findings effectively1

Therefore, knowledge of ISO 9001 requirements and ISO 19011 audit principles are essential for every member of an audit team auditing an ISO 9001 quality management system.