The Douglas/Jeroloman collision is an example of both players doing things that should be against the rules. The only benefit the catcher sees from standing with his foot on the plate is measured in milli- or even microseconds. When Douglas places his foot on the plate, however, he's also requiring Jeroloman to initiate contact in order to score. At the same time, Jeroloman makes no effort to improve his chances of scoring by launching himself at Douglas. In fact, if Douglas catches the ball cleanly, it's hard for him to miss the tag, since Jeroloman is launching himself right where Douglas his going to be holding his glove. If he slides feet-first into the plate, Douglas almost certainly can't tag him. What Jeroloman did wasn't just stupid for being dangerous, it was stupid from the perspective of just trying to score. In any event, the catcher shouldn't be allowed to force the player to initiate contact the way Douglas did (if Jeroloman slides, the chances of someone breaking an ankle are pretty high) and the runner shouldn't be allowed to launch himself at the catcher. The latter should result in an automatic out, ejection, and suspension, no exceptions. It's gratuitously dangerous.
The question of penalizing the catcher is more problematic. The problem here is that home plate is like first base in that it can be overrun without fear of being thrown out, but most plays at the plate are tag plays, not forces. If we want to prevent injuries, we need to decide if the runner should have the right to run full speed through the bag--er, plate--if he thinks that's the most effective way of avoiding a tag. One option would be to say that the runner only has the right to slide into the plate, not run through it. That might sound like an odd way to play, but if you think about it, overrunning first base is kind of odd, too. We're just used to it. If that becomes the case, you'd have more traditional-looking plays at the plate, where the catcher straddles the plate to wait for the ball and the runner slides underneath him. This might lead to more problems, though, as catchers working with home plate umpires unused to calling interference at the plate would have an incentive to set up further up the third base line and force the runner into a slide early. I could see a lot of farcical plays as runners were forced into gymnastics to try to reach the plate without hitting the catcher up high.
If the runner is going to be allowed to run through the plate, then the catcher needs to be told that standing where a runner will pass at full speed, even if he's already scored, is off-limits. However, that's going make it harder to apply a tag, as the catcher will have to stand further up toward the mound or behind the plate. It would lead to a few more runs, because the time it takes to get the ball from a fielder to a place where the catcher's glove can tag the runner, but it wouldn't reduce the total number of exciting plays at the plate, because runners and coaches would go for it more often. I'd assume most catchers would set up in front of the plate and try to position the glove as close to the path of the baserunner as possible, both to minimize the time before they're ready to apply the tag and the likelihood that the ball hits the runner and bounces away, allowing other runners to advance. For interference rule purposes, therefore, it would make sense to give the catcher the right to stand anywhere in fair territory, and award the run and an extra base to any other baserunners if the catcher stands in foul territory (where 99.99% of runners attempting to score are coming from varying angles) and impedes the runner in any way. I tend to prefer this option, because it makes enforcement of the interference rule simpler and less likely to be required.
