Maybe my theory of the "event" isn't so crackpot after all in the mass product liability context. The rule as it stands tends to incent a company to issue a recall, but maybe it doesn't make sense to treat the last person injured differently than the first person.
Some injuries will happen before the manufacturer even knows about the defect (that's how the manufacturer finds out). At the same time, there will never be 100% certainty that a product recall brought in all possible defective saws. Maybe there should be some kind of reasonability analysis.
This is a substantive law question, in negligence law. The plaintiff's argument is that the negligence occurred in the design or manufacture of the product. The manufacturer wants people to look at the entire course of conduct, including steps taken to protect consumers after the defect became known. So this issue is resolved (perhaps varying by jurisdiction).
For the real answer, you might need to consult a products liability specialist. There may not be a one-size-fits-all rule (i.e., the subsequent remedial measure fixing a building entrance-way after a slip-and-dall may be treated differently than one for a mass product liability). Well, Rule 407 is what it is, but it might get handled differently depending on context.
People will seek a legislative fix to this problem, in other words.
And remember Lilly's point about the probative value of the size of settlement offers: a high offer by a defendant might seem to indicate a belief that the plaintiff's case is strong, and a low offer ("a nuisance value" or "litigation cost" offer) might not say much about the case. So we don't want people sacrificing their right to defend their side just because they made a realistic offer, or the other side to be unreasonable in the negotiation because high offers would work in their favor at trial.
There are permitted uses, of course: proving bias, proving/disproving allegations of obstruction or delay.
Plaintiff's counsel likes to open discussions about negotiation before even filing suit: litigation costs come out of someone's pocket, and you can settle for less and still come out ahead (this is when you're on a contingency fee basis). Even on a non-contingency basis, your client is generally someone injured, and might not have deep pockets at all. So you try to open up a discussion as soon as feasible. If you can settle the claim with a couple of phone calls to a claims adjuster (this is for cases where there's an insurer), it's a great payday. A $30K cut of a $100K result is a lot nicer if you've only done a few hours' work, as opposed to all kinds of litigation.
Defendants might feel the same way: they'd rather pay plaintiffs with legitimate claims than just pay lawyers (not all insurers feel this way; some just don't pay claims easily as a matter of corporate policy because they don't want a reputation as a pushover).
And even within one insurance company, there may be different adjusters. So if you're getting all kinds of phony or bad-faith offers to compromise, you can use them if the defendant is claiming there has been undue delay. It wasn't because I was dragging my feet-- it's because you were stringing me along!
Universal wants to offer evidence that a settlement was reached, and that therefore their actions were not a breach. American wants that evidence excluded under Rule 408. But they can't have it both ways: they want to use the account rollovers as evidence of breach, but they don't want Universal to be able to say why they were rolling over accounts. Universal can introduce this evidence in its own defence (i.e., to explain its own actions): that's not one of the prohibited uses.
Why is that allowed under 408(b)? Because that's not an exhaustive list, it's an illustrative one.
The rationale is self-evident: you'll get fewer offers of help, if they're seen as a concession of liability. We want people to get medical help as quickly as possible, because that's when it works best.
Why do this? Because settling criminal cases is a social good just like settling civil cases.
410 isn't a two-way street, though: it only protects the defendant. On the Government's side, there's no individual. Very few statements by prosecutors or law enforcement are admissible as statements of a party opponent. So it's really the defendant (and the defense attorney) who have the most at stake: it's very hard to offer the government's statements against the government.
Also, Rule 410 has its own little rule of completeness (like a mini Rule 106) built in. See 410(4)(i). So if part of the plea discussion are offered by the defendant, the government can require other ones.
This is a bit of a frustrating rule to criminal defense lawyers-- it doesn't come up that often, but when it does it's a pain. In many federal cases, snitching is the foundation of the game. When your client is arrested, the DEA (or whoever) says: you can help yourself, nobody knows you've been arrested yet, we're looking for higher-ups, go cooperate with us, and we'll go to bat for you with the prosecutor; we're prepared to tell the prosecutor not to charge you with the gun or to cap you at five years.
Your client has just been arrested, there's time pressure, and there's no counsel available to him. So he starts making all kinds of admissions: are those plea negotiations? No-- it's not any of the first 3 sections, and it's not with an attorney for the government. The AUSA is orchestrating this, of course, but isn't out there on the street with the agents. It's hard to prove that the agents' statements were directly authorized by the prosecutor.
Footnote: Rule 11 of FRCP is arraignment, etc. (that's 410(3)).
Note that in actual plea negotiations, it's just a meeting of lawyers: the defendant isn't present to be badgered.
So, really, Rule 410 doesn't really protect the kinds of discussions we might want to encourage (if we think that cooperation is a social good-- this is debatable... perhaps a nation of snitches doesn't take us anyplace good). Nearly everything that happens on the street (where most deals are struck between the government and the newly arrested) isn't covered by 410.
You can come up with apparent correlations, but they are false. There's just no relevance here (or at most very slight).
This is an easy rule, just like 409.
Efficiency in general, actually. We want to avoid discovery disputes, waste of judicial resources, etc. It's not just trial avoidance.
Maybe as an over-aching note, tie these back to Rules 401 and 402. There's a cost to these rules, though. They save, in terms of efficiency and maybe social goods, but they cost us perhaps some relevant evidence. And, in general, the rules are loath to exclude the relevant. So that's why the limitations in these rules are as carefully drawn as they are: none of them are blanket exclusions-- they just exclude certain evidence from being offered for certain purposes.
Also, as a practical matter, in a case in which punitive damages are a potential issue, whether the defendant has liability insurance (or indeed what the defendant's assets are) is relevant, but this is an issue that has to be bifurcated. Your assets or insurance aren't relevant to whether you acted wrongfully, but once the question is resolved against defendant, the jury needs to hear about these things so they can decide what's an appropriate exemplary/deterrant award.
So Rule 411 doesn't bar evidence of liability insurance in the question of punitive damages (see BMW of North America v. Gore), but just as proof/disproof of liability.
606 isn't entirely ridiculous-- jurors do get called as witnesses in post-verdict matters. No lawyer in his right mind would allow a witness to get onto the jury. Rule 606(b) does come up sometimes: a juror brings a bible or a reference book into the deliberation room, for example. There might be a question as to whether extrinsic material was considered.
If a lawyer vouches for the witness, that violates the power of the oath, to some extent. We also want to avoid gamesmanship by witnesses who might play one side off another. Also, sometimes the person you're calling is adverse to you. And that's a pretty big point.
Note that it's now misconduct to vouch for a witness in closing argument: that's a improper argument, and the objection is "vouching." So not only have we abandoned the voucher rule, we now actively prohibit it.