The duty to warn arises in product liability cases, as manufacturers can be held liable for injuries caused by their products if the product causes an injury to a consumer and the manufacturer fails to supply adequate warnings about the risks of using the product (such as side effects from pharmacy prescriptions) or if they fail to supply adequate instructions for the proper use of the product (such as a precaution to use safety glasses when using a drill). If the manufacturer fails to supply these warnings, the law will consider the product itself to be defective.