In products liability law, a post-sale warning exists when the manufacturer learns after a product is distributed that it failed to warn of a danger that was knowable at the time of sale. However, a manufacturer has no point-of-sale duty to warn of dangers from unforeseeable misuses or alterations of its products. When a product develops a post-sale problem because of an improvement in the state of the art (e.g. because of the development of a more effective safety device), there is no requirement that a manufacturer seek out past customers and notify them of changes in the state of the art, as that would be unreasonable and inconsistent with the rule that a product's compliance with the state of the art is judged no later than the time of sale. When a duty to warn is present, it extends to foreseeable users of a product, including, the employees of the purchaser, at times. However, this duty to warn may be discharged by warning only the employer when it is a knowledgeable industrial user of the product, is well aware of its risks, and can be expected to supervise the use of the product and issue appropriate warnings to its own employees. Some courts, such as the Seventh Circuit in Gracyalny v. Westinghouse, fail to give this principle proper weight.
John S. Allee,
Post-Sale Obligations of Product Manufacturers ,
12 Fordham Urb. L.J. 625
Available at: http://ir.lawnet.fordham.edu/ulj/vol12/iss4/1