Is it ever right to take a human life?

Only in self-defense, while defending someone who cannot defend themselves, or when ordered to do so by a government. Outside of that, it is unacceptable and illegal to kill another human being.

There was a case recently where a retired police officer killed a man in self defence because he was threatened by the man using a cell phone. Governments often order its people to kill others, often to commit genocide. There is no justification for a person to kill another person. Whether it is legal or not, whether you would be punished for not killing or not.