Can someone explain to me what the purpose of the shield law is? Whether Chen is protected under it or not seems like a technicality to me. I'm more interested in how the law is supposed to benefit society.

Is the idea that journalists should be able to keep their sources confidential? Or that they should be be immune from retaliation for printing unflattering stories of the government and police? Is it to protect whistle blowers? Is it supposed to protect journalists who have broken the law?