Steven Judge is the former Director of the Ionizing Radiation Department at the Bureau International des Poids et Mesures (BIPM) in Paris, the institute that is at the heart of the international measurement system. He has a background in nuclear physics research, and he has worked in various roles at the National Physical Laboratory, the UK nuclear industry and at a radiopharmaceutical manufacturer. Quality assurance has been a key aspect of his career, including ensuring the accuracy and reproducibility of measurement standards relied on worldwide for medical imaging, cancer therapy and environmental protection. A trained technical assessor for the United Kingdom Accreditation Service, he has contributed to the development of ISO standards and was responsible for quality assurance issues at the BIPM.