Only a liar has to swear. Years ago, before Madelyn Murray Ohare and the other atheists kicked God out of the courtrooms, people were afraid to lie and especially if they swore to God not to lie. Jesus says not to swear by things you have no power over anyway. When you get married there used to be wedding vows that established the authority in the family and ended most arguments before they began. Many men abused that authority and lost their respect and many women never intended to keep their vows in the first place. Vows and oaths only work for honest people who don’t need them.