The Rule in Shelley's Case is a law that states that if real property is passed on to a person and a remainder of this property is designated for heirs, then the initial person who it was passed on to will have the absolute right of the property.
This rule was created in the 1500s in England to help clear up property right disputes.
This law is mostly outdated now, and is a historic example of a common law. However, it is still often studied and referred to. There are many reasons why people would set up remainders when bequeathing property. For example, a man may want to pass a home on to his son, and then to his grandson.
However, under the Rule in Shelley's case, if a single grant for a freehold estate was used, then the son would retain the complete ownership of the property, and not the grandson.