'Lawful' in the Bible

But certain of the Pharisees said, Why do ye that which it is not lawful to do on the sabbath day?

how he entered into the house of God, and took and ate the showbread, and gave also to them that were with him; which it is not lawful to eat save for the priests alone?

And Jesus said unto them, I ask you, Is it lawful on the sabbath to do good, or to do harm? to save a life, or to destroy it?

And Jesus answering spake unto the lawyers and Pharisees, saying, Is it lawful to heal on the sabbath, or not?

Is it lawful for us to give tribute unto Caesar, or not?