Federal Rule of Evidence 407 prohibits the introduction of subsequent remedial measures for the purposes of demonstrating negligence, culpable conduct, or product defect. But the rule breaks down, in application and purpose, when a defendant undertakes the new safety measure after the plaintiff’s injury, but before the defendant had knowledge of the loss. Such a situation is not uncommon. Would-be defendants frequently improve their products and product safety for a variety of reasons. Toxic exposure cases, where exposure often predates diagnosis of the injury by a decade or more, represent a prime example of cases where defendants are likely to have made significant product or warning improvements which, if taken before the plaintiff’s exposure, may have prevented the injury. Should evidence of these improvements be admissible? The literal text of Rule 407 suggests not. Yet allowing such measures into evidence may not have the same chilling effect as when the measure was taken in response to the plaintiff’s injury. In such circumstances, it can be argued the defendant never feared the measure would be used against it. Since the policies behind Rule 407 may not support the exclusion of such evidence, should it still be applied? This article explores Rule 407, its policy underpinnings, courts’ differing interpretations of the rule, and how it should be applied to defendants who take subsequent remedial measures without knowledge of a plaintiff’s injury. Finally, we suggest an interpretation of and amendment to Rule 407 that clarifies the rule and furthers its policy bases.