I beg to differ. I'll open with you being correct in that outright slavery is illegal in my country. At least in the US there are different legal precepts that allow you to "possess" a variety of rights to your spouse. One large and important one is that in some states, you cannot rape your wife. At least without specific legal codes being met and of course, proven in a court of law. There are other concepts that could be construed as ownership (alimony, moving restrictions during divorce finalization, etc) to varying degrees. And of course if you lock someone in your basement you can obviously possess them until they are freed or you are dead. It's not morally right obviously but it is possible and does happen.