If your estate plan and related documents are properly and carefully drafted, it is highly unlikely that the court will disregard your wishes and award the excluded child an inheritance. As unlikely as it may be, there are certain situations where this child could end up receiving an inheritance depending upon a variety of factors.
To understand how a disinherited child could benefit, you must understand how assets pass after death. How a particular asset passes at death depends upon the type of asset and how it is titled. For example, a jointly titled asset will pass to the surviving joint owner regardless of what a will or a trust says. So, in the unlikely event that the disinherited child was a joint owner, that child would still inherit the asset because of how it was titled.
Similarly, if you left that disinherited child as a named beneficiary on a life insurance policy or retirement plan asset, such as an IRA or 401k, that child would still receive some of the benefits as the named beneficiary even if your will stated they were to take nothing. Another way such a “disinherited” child might receive a benefit is if all other named beneficiaries died before you.
So, assume you have three children and you wish to disinherit one of them and you state you want all of your assets to go to the other two, and if they are not alive, then to their descendants. If those other two children die before you and do not have any descendants, there may be a provision that in such a case your “heirs at law” are to take your entire estate and that would include the child you intended to disinherit.
If you wish to disinherit a child, all of these issues can be addressed with proper and careful drafting by a qualified estate planning lawyer.