When a testator drafts a will, they're supposed to detail all of the assets that they own and what their final wishes are as it relates to who they'd like to become the new owner of them. Heirs often don't find out if they're set to receive any of the estate's remaining assets until once the testator has died. By the time they find out what their final wishes were, they're often blindsided by hearing that they're not set to receive anything.
Although the more formal name for this document that details their final wishes is a "last will and testament," it's not always the end of the road. It's possible to challenge it, especially if you believe that someone exerted some type of undue influence over the testator or that they were mentally incompetent when they drafted it.
In order to be able to contest a will, most jurisdictions' probate courts require for you to be an "interested party". This is simply a formal way of describing someone that may have been in the line of succession or otherwise slated to inherit the decedent's assets.
There are multiple grounds on which you can contest a will in New York.
If you can produce medical records showing that the testator was mentally incompetent at the time that they drafted their will, then you may be successful in petitioning a judge to have it thrown out. You may also succeed in doing so if you can show that they neglected to update their will after the birth of a second or subsequent child, although they'd done so after the first was born.
Interested individuals in Queens may also be eligible to contest wills if they have proof that the testator was subjected to undue influence from others at the time that they drafted the document. A judge may throw it out if you're successful in proving that someone else persuaded your loved one to make changes to their will.
Each state has different procedures for what happens after an interested individual contests a will. An estate planning attorney can both help you plan for the future and can be there for you when you need to pick up the pieces when things may have not gone as planned.