Enforcing exception handling programmatically is only a part of the puzzle. The article by Bruce Eckel mentioned in this thread rests a good hunk of its case against checked exceptions on the claim that lots of programmers don't use them properly, which seems like an odd kind of criticism to make, IMO. Of course, he does make the valid point that, even if you implement checked exceptions in your framework, that you'd still need to make sure the team is dealing with them properly.
A better title for Eckel's article, I think, would have been Checked Exceptions are not a Magic Bullet, but I would have thought it obvious that there are no magic bullets. I think you're going to have to cope with this issue, as with nearly every issue that comes up in designing large systems, by "preaching diligence to every member of the team." And I'll parrot Ovid: make sure everybody runs tests. Anything else is the bad kind of lazy.
update : fixed a typo.
If not P, what? Q maybe?