When it comes to where their property will go when they die, a person may have very strong views on who they don't want to receive any of their property.
There are a variety of different reasons why a person may desire to exclude a given person from receiving any property from their estate when they pass away. Whatever a person's reasons for this desire, a will may be able to help them achieve their goal. Generally, one of the types of terms you can include in a will is a clause that blocks a given individual from receiving any estate property. In most cases, when this term is included in a will, it will be enforceable, even if the individual the will excludes from receiving property would have been entitled to an inheritance if not for the will.
As a note, there are some limits to disinheritance clauses. For example, here in Michigan, such clauses will generally not be able to disinherit a deceased's spouse unless certain specific conditions have been met.
Also, disinheritance clauses are sometimes the target of a will challenge by the disinherited individual. Thus, when including disinheritance terms in a will, it can be important to take steps to best ensure there would not be grounds to successfully challenge these terms.
When a person brings a skilled estate planning attorney in to help them form a will, the attorney can provide them with guidance on what can help ensure that the terms they include in their will, such as disinheritance clauses, have the desired effect.
Source: FindLaw, "Top Ten Reasons to Have a Will," Accessed Jan. 11, 2016