The opposite team getting a point sounds good, but sometimes it really is a mistake.
supreme might step in front of me, I might walk on her mine, topz might go Rambo and kill everyone with a bomb - these aren't on purpose. We're not trying to police the accidents. We're trying to punish the idiots who abuse the format and gladly kill a teammate so the other team can't.
How about this:
If you kill a teammate, it's the same as suicide - only worse! You lose EVERY weapon except your starter ammo: a few pistol shots, a few shotguns, 60 p-gun.
So for the people who do it on purpose, they have to run around and reload. They just can't kill a teammate and then keep fighting like normal. They'll have NO bombs, NO mgun, NO M4, NO sniper, etc.
And for the people who do it accidentally, well, they won't do it often enough for there to be a real issue about having to reload. They'll just have to be more careful.
For the landmines - I was thinking that if I teammate steps on your landmine, both should die and have to wait a full spawn period to get another mine.
(It doesn't seem like a big punishment at first, but it works out: in a smaller map, both spawning gives you the advantage to set-up on them, and in DOM, those 5 seconds give you time to move the dog, likewise with CTF. So it's a big punishment!)
I personally watched a few of our buddies walk on their own mines and each other's mines when they had low health.
Once or twice - okay, it's an "accident." But they did this about 20 times in the course of one game. Nobody is that stupid.
(I did it before, but that's because my stupid monitor settings show both as the exact same blue. Now that's changed and I don't do it anymore. So wtf guys? That's just cheap!)
It doesn't give the other team a point, so this is a cheater's favorite way to save a point off the board if they're running around with 30HP and no chickens are cluckin' around.