Individuals in California may not realize that a will does not necessarily stand as written but can be challenged. It is a rare occurrence that rarely occurs, but there are a few grounds upon which a will may be successfully challenged.
If there is more than one will and an effort is being made to push the older will through the courts, this could be one reason. A will might also be challenged on the grounds that there are no witnesses or too few witnesses or that the will was prepared and signed under duress or through fraud or forgery. A will may also be challenged on the grounds that the testator lacked testamentary capacity. This refers to mental capacity, and it can mean that the testator may have had dementia, been insane, been under the influence of a substance or may have been a minor. There may be exceptions for minors who are in the military or married.
There are also grounds upon which some individuals may try to challenge a will but are unlikely to be successful. For example, if the testator made a will in one state and then moved to another prior to dying, that will would probably be valid under the probate laws of the new state.
An individual who does believe a will should be challenged may wish to work with an attorney. For example, the challenger could be a child of a testator who shortly before passing away changed his or her will to leave everything to a caregiver. Such a challenge could be predicated on the grounds that the parent may not have been of sound mind at the time of the change in beneficiaries and may have been unduly influenced by the caregiver.
Source: Findlaw, “Reasons to Challenge a Will“, November 26, 2014