So, you want to disinherit someone, do you? Well, that may or may not be easy to do, depending on who you are trying to disinherit. If it's not your spouse or child, simply don't mention the person in your will.
However, if you are trying to disinherit a spouse or child, you are going to run into some difficulties. First off, you may be unable to disinherit your spouse at all. In many states, what is yours is also your spouses – he or she owns half of what you own in community property states, though you can certainly leave your half of the property and estate to someone else.
If you don't live in a community property state, then your spouse does not legally own half of what is yours. However, the laws in those states say that your spouse has a legal right to a portion of your estate even if he or she is not named in the will, assuming, of course, that your spouse challenges the will.
Here's an example. Many states state that the spouse is entitled to one-third of your estate. If you die without naming your spouse in your will, he or she will automatically receive half or your estate. If you leave a will, and only leave your spouse, say, one-fifth of your estate, he or she can challenge the will to get what is legally his or hers – the one-third (or one-half, depending on the state).
As for a child, you can disinherit him or her if you specifically state that you are leaving the child out of the will. If you fail to mention the child at all, many state laws assume you forgot and simply grant that child his or her share. If this situation applies to you, I assume that your child did something terribly wrong to deserve disinheritance.
Wills - Disinheritances
This doesn't happen very often, to be honest. When it does, it's usually by someone who feels cheated out of his or her share of the will. However, legally, only a spouse is entitled to a specific share. So, to successfully challenge a will, it does little good to argue that the person making out the will made a mistake or cheated you. Instead, your best shot is to challenge the validity of the will, i.e. arguing the signature was forged, that the person making out the will was not of a sound mind, or that he or she was coerced or unduly persuaded by someone else.
Wills - Challenging a Will