Ireland's old marriage laws were a bit strange...

Under Brehon laws that governed Ireland as long ago as 600 AD, a man had the right to divorce his wife if she committed adultery, stole things from him or generally “made a mess of everything.” But rules of conduct in marriage were indeed complicated. Under some circumstances, it was legal for a man to hit his wife — as long as he did not leave a mark. If he did, his wife would be entitled to financial compensation from him for the blow. A woman could divorce her husband if he was either impotent or homosexual, and women had the right to own property independently within marriage. The power of Brehon laws rose and fell in Ireland for several centuries, competing the influence of both church and British laws. They governed parts of Ireland, however, all the way up until the 17th century.