You’ll need a strong case to fight this type of claim, because the options are limited.
It does not seem fair that a father would change his will to disinherit a son. However, unfortunately that does happen. If the will has been revised properly, following the laws of the state, there is not a lot that a disinherited child can do. That’s the unpleasant reality, says nj.com in the recent article “My step-mother changed my dad's will. I got nothing. What can I do?”
In the U.S., for the most part, a person has the right to leave his or her property and assets to whomever he or she chooses. It’s called "freedom of disposition." However, in the United States, some classes of beneficiaries have the right to take 'against' the will."
A surviving spouse can claim an elective share of an estate, if he or she is disinherited. The rules for granting an elective share are complicated. However, the thought behind the law is that a spouse has the obligation to provide for the support of his or her spouse and by disinheriting the spouse, they’re violating this duty.
In the U.S., adult children typically don’t have any right to inherit from a parent.
To overcome this, a child would need to prove that his father didn’t act of his own free will. The child would need to show that his stepmother “unduly influenced” his father to change his prior will and leave everything to her. If successful, the father’s property would be distributed according to his last valid will, or if there is no will, according to the intestacy statute.
Proving undue influence can be quite difficult to do. The child would have to show that the step-mother was in what is known as a "confidential" relationship with the father and that there are suspicious circumstances. If so proved, the burden of proof shifts to the step-mother to show that she didn’t unduly influence the father.
If the father was diagnosed with dementia, had stopped working and can be proven to have diminished capacity, there might be the ability to demonstrate undue influence. However, if the father is still working and functioning at a normal level, it would be very hard to prove a lack of free will. This kind of a claim is very technical, and every case is determined on the specific facts.
Anyone facing this type of situation should speak with an experienced estate planning attorney, to see if they have any chance of success with pursuing a claim.
Reference: nj.com (February 8, 2019) “My step-mother changed my dad's will. I got nothing. What can I do?”