'Lawful' in the Bible

And the Pharisees said unto him, Behold, why do they on the sabbath day that which is not lawful?

How he went into the house of God in the days of Abiathar the high priest, and did eat the shewbread, which is not lawful to eat but for the priests, and gave also to them which were with him?

And he saith unto them, Is it lawful to do good on the sabbath days, or to do evil? to save life, or to kill? But they held their peace.

For John had said unto Herod, It is not lawful for thee to have thy brother's wife.

And the Pharisees came to him, and asked him, Is it lawful for a man to put away his wife? tempting him.

And when they were come, they say unto him, Master, we know that thou art true, and carest for no man: for thou regardest not the person of men, but teachest the way of God in truth: Is it lawful to give tribute to Caesar, or not?