Suppose a pedestrian is walking along the sidewalk in front of your house and trips over a large crack in the sidewalk, sustaining serious injury. The pedestrian sues you, claiming your failure to maintain the sidewalk was the proximate cause of the injury.
Upon inspection, it is obvious that the sidewalk is in poor condition and should have been repaired. But should you repair it now? Won’t that look like an admission on your part that the sidewalk was defective?
This conundrum is resolved by the “subsequent repair doctrine.” This rule of evidence provides generally that when a party takes measures that would have made an earlier injury or harm less likely to occur, evidence of the subsequent repair is not admissible against that party to prove negligence or wrongful conduct. The purpose of the subsequent repair doctrine is rooted in the common sense notion that society is better served by having repairs made to prevent further injuries, even if done after the fact. In our example, the pedestrian would not be permitted to introduce evidence that you made a repair to the sidewalk two days after the injury (presumably trying to show that you knew the sidewalk was in bad shape) because society wishes to encourage people to make repairs, even where it might otherwise look like an admission of fault.
– Kevin Palmer