I'm sure this has been posted here before,

[PoindexterOglethorpe]

but it bears re-posting.

1967 - Jayne Mansfield is tragically killed when her car runs under the rear end of a tractor trailer. Since then, all trailers have a DOT bar at the rear to keep cars from going under them.
1982 - Seven people die when Tylenol packaging was tampered with in Chicago. Since then, it takes a PhD, channel locks, and a sharp object to get into a bottle of pills.
1995 - A bombing in Oklahoma City used a certain kind of fertilizer, solution grade ammonium nitrate, and killed 168 people. The government imposed severe restrictions on the purchase of that fertilizer.
2001 - One person attempts to blow up a plane with a shoe bomb. Since then, air travelers have to take off their shoes for scanning before being allowed to board.
Since 1968 - 1,516,863 people have died from guns on American soil. Gun violence kills an average of 168 people every two days.
Now, the problem apparently can't be solved except with thoughts and prayers

[PoindexterOglethorpe]

2. There is a time limit on presidency.

Not sure what you are otherwise meaning.

[PoindexterOglethorpe]

5. Those four things are examples of how only one particular disaster

led to a huge change in a law.

The Presidential term limits did not come about as a result of one disastrous presidency, although Republicans might possibly disagree. Nonetheless, it's simply not comparable.

[Haggis for Breakfast]

4. Dear Poindexter

Yes, it has been posted before, but it is so noteworthy that I'm sure no one minds reading it again. And again.