I've been reading up on features to make table saws safer and in one forum there was a post that said, basically, manufacturers have had no incentive to license a table-saw safety device from the inventor because doing so would only increase their exposure to product liability lawsuits relating to their older models: developing a safety feature themselves or licensing one developed by a third party would be ipso facto proof that they are aware their previous models are unsafe. In the US product liability arena is there really such a paralyzing disincentive for manufacturers to make safety improvements to their products? Does a manufacturer really incur risk by making safety improvements?

  • 1
    "Not the safest possible by all known methods" <> "Unsafe"
    – tbrookside
    Aug 14, 2022 at 12:03
  • @tbrookside I don't want to quibble. Clearly you understand the gist of the question? If you like, read "to some degree" or "in some respects" after the adjective "unsafe".
    – Tim
    Aug 14, 2022 at 12:30
  • In this case, the latest saw safety devices are very expensive, so I suppose that if you make a saw with them, he concern might be how can you justify not putting that expensive safety on every saw in your line. Aug 14, 2022 at 15:26
  • @ScottSeidman What liability risk would require the manufacturer to put the safety device on every saw in its lineup, once it has put it on any model?
    – Tim
    Aug 14, 2022 at 17:14
  • The answers center around the idea that old products can't be evaluated to safety standards of new products. I'm pointing out that this doesn't preclude current products being evaluated at the standard for other current products. Aug 14, 2022 at 17:26

2 Answers 2


In order to avoid this perverse incentive, Rule 407 prohibits the use of subsequent safety measures as evidence for liability:

Rule 407. Subsequent Remedial Measures

When measures are taken that would have made an earlier injury or harm less likely to occur, evidence of the subsequent measures is not admissible to prove:

  • negligence;
  • culpable conduct;
  • a defect in a product or its design; or
  • a need for a warning or instruction.

But the court may admit this evidence for another purpose, such as impeachment or — if disputed — proving ownership, control, or the feasibility of precautionary measures.


  • If the new safety feature can show that a precautionary measure was feasible, could that expose the company to risk for anything that is not in one of the inadmissible categories (negligence, failure to warn, etc) ?
    – Tim
    Aug 13, 2022 at 1:09
  • To enlarge upon my comment above, could subsequent safety measures implemented by the manufacturer expose the manufacturer to risk because of prior bad-faith marketing, if, say, they had made essentially false statements in the marketing literature such as "The safest saw money can buy!"? Or are false marketing claims subsumed under "culpable behavior"?
    – Tim
    Aug 13, 2022 at 10:19
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    This is a good answer that could be improved by mentioning that Rule 407 is one of the Federal Rules of Evidence and applies in federal courts. It is a general rule, as explained in the comments, and applies to more than the product liability question of the OP. I believe all of the states have a similar rule for state proceedings, although it gets complicated with respect to government liability for defects on roads and in public places.
    – Wastrel
    Aug 13, 2022 at 13:39
  • The perfect is not the enemy of the good.
    – EvilSnack
    Aug 14, 2022 at 4:52
  • I was told hospitals with two x-ray machines are in trouble if one breaks down and is replaced by a newer and better model. Because everyone x-rayed with the old machine can claim they didn’t get the best possible care. No idea if it’s true.
    – gnasher729
    Aug 14, 2022 at 9:19


Quite likely, the manufacturer is increasing their risk if they don’t incorporate known safety improvements

Product liability law is nicely summarized here.

With respect to older products it says:

Expected levels of safety differ for older products because they cannot be expected to be as safe as brand-new products. Similarly, older models of products would not necessarily be considered defective simply because more recent models have improved safety features.

And, one of the things a court must consider is “the time when the product was supplied” which includes considering what was reasonable practice at that time.

  • An easy retrofit to products already in the field is not feasible in the particular case being discussed on the forums I mentioned in the question, FWIW. But what if that was possible? Would that change the calculus regarding "older products" and "reasonable practice at that time"? Does the present become any more relevant than the past when an easy retrofit is possible? Would it continue to be reasonable to say "Expected levels of safety differ for older products because they cannot be expected to be as safe as brand-new products" ?
    – Tim
    Aug 13, 2022 at 10:02
  • Easy as in rolling out a firmware update (are they (still) expected? Or how far beyond?), or as in only needing minimal physical change? Aug 14, 2022 at 11:48
  • @Deduplicator: Let's say for the sake of the hypothetical that a retrofit is easy-peasy, cost and logistics both de minimis.
    – Tim
    Aug 14, 2022 at 17:19

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