Prescinding from the religious issue, there are so many other common sense reasons why any civilized society should outlaw polygamy for the common good. Some of those reasons — reasons I would never have thought of, since I don’t know any Mormons — are brought up in this article. Here’s a clip:
Catholic Online: Some of the polygamous wives were called to witness in favour of the practice of plural marriage, although Oler and Blackmore were not present at the proceedings. On Jan. 25, one wife testified anonymously that she married at 16 to the husband of her sister and had nine children with him (her sister had 10). She explained the difficulties the three of them faced. “It takes a considerable amount of faith and determination to live the right way,” she said. Their polygamous relationship, she said, will let them attain the “highest degree of God’s celestial kingdom.” The wife can only enter the “celestial kingdom” if the husband “exalts” his wife through marriage.