Marriage carries with it certain rights. Spouses have an obligation to support each other, even if one spouse just contributes household labor so the other is free to go out to work. Spouses also have obligations to each other after one of them dies, and these obligations translate to rights that states protect with their probate laws.
Unless you live in Georgia, you can't legally disinherit your spouse, and even Georgia law guarantees a surviving spouse a year's worth of income off the top of a decedent's estate before any debts or expenses are paid. All other states provide for something called "elective shares." If you write your spouse out of your will, or leave just a nominal amount, your spouse can elect against accepting what you bequeathed to her, if anything. A spouse has the right to veto the terms of the decedent's will and accept a statutory percentage of his estate instead. State laws vary as to the exact percentage. In Pennsylvania, for example, a spouse receives one-third of the estate, but other states may award more than that.
When There's No Will
In legal terms, a decedent dies "intestate" if he does not leave a will. When this occurs, states' laws of intestate succession take over. Intestate succession relates to a list of kin who statutorily inherit in an order of priority set by state law. The order is set according to what the law assumes the decedent would have wanted, so spouses are always first in line. They must only share the estate if the decedent left any children, either those he had with his surviving spouse or children from a previous marriage or relationship. By law, spouses have a right to at least a portion of the decedent's estate if the decedent dies intestate.
Florida law mandates that a decedent can only leave his home to his spouse and his children, but other states have different ways of securing a surviving spouse's right to the marital home. Some states recognize tenancies held by the entirety between husbands and wives. With this type of deed, the home passes directly to the surviving spouse without the necessity of probate to transfer title. This means the property is usually safe from the decedent's creditors. Joint tenancies with rights of survivorship work the same way. However, these rights to the marital home are elected by spouses. They choose them voluntarily; state laws don't mandate them.
Community Property States
The law works differently in the nine community property states. In these jurisdictions, spouses equally own everything they acquire during the marriage. Therefore, a decedent can only bequeath half a couple's marital property to beneficiaries other than his spouse -- the half that is legally his. A surviving spouse always retains her own half, and she may have a right to the other half as well, if the decedent dies without a will. If the decedent doesn't leave any children and his parents have predeceased him, his spouse has a right to his entire half of the community property. Otherwise, she would receive a share of his half of the community property, with the balance going to his children or, in some states, his parents. Community property states don't recognize elective shares in the same way other states do, because surviving spouses automatically have a right to half the marital estate.