1) safety measures or repairs
2) after an accident
3) is inadmissible
4) to prove culpable conduct
5) and, in a PRODUCTS LIABILITY ACTION, is inadmissible to prove DEFECTIVE PRODUCT DESIGN.
6) Can offer it to prove other things: like
a) Control or responsibility
b) Also to rebut the defense of NO FEASIBLE PRECAUTION:
i) D says there was nothing he could have done to avoid this accident
ii) P offers Ds actions modifying it
This is admissible to prove their were feasible precautions available. D is arguing more than just D was not negligent, D is arguing the accident was impossible. When this argument is made, the law says you made a repair after the accident, so apparently the accident could have been avoided, so its only fair that D can admit this evidence.