When someone is a child, they are not considered to have testamentary capacity. This is why someone who is under 18 years of age generally cannot write a will. They are not considered to have the mental capacity to do it at this time.
Once you’re over 18 years of age, then you can make a will, and it is presumed that most adults do have the capacity to do so. Without other evidence to show that they do not, they have the ability to write out an estate plan.
However, an adult can lose their capacity under certain situations. This could have happened if they have Alzheimer’s or another type of degenerative brain disease. They could have dementia or something of this nature. Once this happens, it brings into question the validity of the will because the heirs may ask if it was actually the mental disorder that caused their parent to write the will in that fashion.
Why is this an issue?
This is a big issue regarding will contests if the estate plan had been changed relatively close to the person’s passing and they had already been diagnosed with some sort of mental impairment, disability or disease.
Heirs may feel that the older version of the estate plan needs to be honored and that the newer version is inaccurate because the individual did not have the mental capacity to really understand the impact of all the decisions that they were making. For this reason, those heirs will sometimes challenge the will in court.
If you and your family find yourself in this situation, it can certainly be complex and there are a lot of different details that need to be considered. Be sure you understand your legal options entirely.