What type of estate is granted to Mary, where she can possess it for her lifetime but cannot pass it to her heirs?

A life estate is a type of property ownership that grants the holder the right to use and occupy the property for the duration of their lifetime, but it does not allow them to transfer ownership to their heirs upon death. In this case, Mary is granted a life estate, which means she has complete control over the property during her life, but once she passes away, the property will revert to the grantor or another designated party specified in the original deed.

This arrangement is created to ensure that while Mary has the benefit of living in or using the property, the future interests are predetermined, thus preventing her from passing it on to her heirs. Life estates are commonly employed in estate planning to provide for one individual while ensuring that the property eventually moves on to another party. This is an essential aspect of estate law, as it defines ownership rights and limits in relation to life estates.