This article outlines the case for a business duty of care to exercise human rights due diligence, judicially enforceable in common law countries by tort suits for negligence brought by persons whose potential injuries were reasonably foreseeable. A parent company’s duty of care would extend to the human rights impacts of all entities in the enterprise, including subsidiaries. A company would not be liable for breach of the duty of care if it proves that it reasonably exercised due diligence as set forth in the Guiding Principles on Business and Human Rights. On the other hand, a company’s failure to exercise due diligence would create a rebuttable presumption of causation and hence liability. A company could then avoid liability only by carrying its burden to prove that the risk of the human rights violations was not reasonably foreseeable, or that the damages would have resulted even if the company had exercised due diligence.