I don't see why Brit troops would face prosecution if it is US forces that use the weapon. If Brit Forces call in the mud shifters then they get what ordnance they are given, and even then the guy dropping the weapon isn't the one breaking the law, the gov't owns the bomb in the first place.
On a 2nd point. Perhaps we should make bombs out of marshmallows now just in case it hits someone on the head. While we are at it, paint it a nice colour so that it doesn't offend anyone when it is dropped and doesn't go bnag -it is also environmentally friendly and will dissolve over time, or be eaten by children. The marshmallow would be useful in absorbing the loud noise from the bnag action, thereby not waking anyone up that lives near the target.