“It’s too dangerous for them to use correspondence, phone calls or consular meetings” to raise concerns about conditions, he said. Humphrey said he did not hold Tesco responsible, if it were found to have used prison labor. “China makes it impossible for a company to drill down right to the bottom of the supply chain to identify the small contractors,” he said. He added that he believed the prisoners involved were working against their will. What they mean is that they have been put in a position where they are coerced,” he said.