'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 entered into the house of God when Abiathar was high priest, and ate the showbread, which it is not lawful to eat save for the priests, and gave also to them that were with him?

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

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

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

And when they were come, they say unto him, Teacher, we know that thou art true, and carest not for any one; for thou regardest not the person of men, but of a truth teachest the way of God: Is it lawful to give tribute unto Caesar, or not?