In most areas, if you are in fear for your life, or the life of someone else. You can take lethal action (kill).
to defend themselves
Use of Deadly Force in DefenseThough I'm sure the majority of people would not take any pleasure in killing another human being to defend themselves or their property, I definitely believe that using deadly force should be a choice they can make without repercussion. ---Can the government use deadly force to protect their personal and government property? The government in the United States is made up of ... the people...
Defendants.
they want to defend themselves
Genocide
Generally, it is best to let people defend themselves. They might not care for the way you go about it.
Porcupines defend themselves with their quills.
Murder, genocide.
Billions. Depends upon your definition of 'know how to defend themselves' is. Pretty much everyone is going to try to protect themselves if they are attacked. If you mean effectively defend themselves it would be a different story. And how many people have taken self defense courses or martial arts is another story all together.
They defend themselves by releasing disgusting slime when attacked.
Porcupines defend themselves with their quills.
To deprive people of the right to defend themselves with a firearm.