I said this because, it states towards the end of 'Our approach to eliminating modern slavery' that "our certified suppliers are audited annually against social... criteria." Also, it does mention that suppliers must be certified and meet the businesses expectations; therefore suppliers having to comply with laws and company's policies.
The company is still in the early stages of developing policies to combat slavery in their supply chain. They do not mention that all their suppliers must comply with laws and company's policies.
p.1 "Our certified suppliers are audited annually against rigorous social, economic and environmental criteria. We are also supporting our other suppliers to achieve certification."
"In 2017 we will expand the assessment exercise to evaluate potential risks at our international stores and thereupon to develop any remedial actions required."