You can't stop accident's, but you can stop muppets using a chainsaw without propper training, that will almost certainly cause an accident to someone other than themselves!
It would be a bit like people driving a car without taking driving lessons, on both accounts you are opperating a killing machines, and should be treated as such.
People that think "I can do that", are usually the ones that need the most training!
But then i am only a Fully Qualified tree surgeon, that has a friend as a nurse in A&E, what do either of us know!!
RM