Not everyone who dislikes a will's terms can contest it. Courts generally require standing, meaning the person challenging the will must have a direct financial interest that would change depending on the outcome — for example, an heir who would inherit more under intestacy law, or a beneficiary under an earlier will who was removed or given less in a later version.

A person with no legal or financial stake in the estate — someone who would not inherit under any version of events — typically lacks standing to contest, regardless of how strongly they disagree with the will's terms.

The most common grounds are lack of testamentary capacity (the person did not understand what they were signing or the nature of their estate at the time), undue influence (someone exerted improper pressure that overcame the person's free will), fraud (the person was deceived about what they were signing or about facts that shaped their decisions), and improper execution (the will was not signed or witnessed according to the state's formal requirements).

Each ground requires different kinds of evidence. Capacity challenges often rely on medical records and witness testimony about the person's mental state near the time of signing; undue influence challenges often focus on the relationship and behavior of the person who benefited; execution challenges focus narrowly on whether the state's signing and witnessing rules were followed.

A will contest is typically filed in the probate court where the estate is being administered, either before the will is admitted to probate or within a specific window afterward, depending on the state. The process resembles other civil litigation — pleadings, discovery, depositions of witnesses like the drafting attorney or medical providers, and potentially a trial if the parties cannot resolve the dispute.

Many will contests settle before trial, particularly where the family wants to avoid the cost, delay, and public nature of litigating in probate court, and where a negotiated division of the estate can resolve the dispute without a judicial ruling on validity.

States impose strict deadlines for contesting a will, and these deadlines can be considerably shorter than general civil statutes of limitations, sometimes measured in months from when probate is opened or from when the contestant received notice. Missing the deadline can permanently bar the challenge, so acting quickly once a concern arises is important.

Given the emotional and financial stakes, and the fact-intensive nature of most contests, consulting a probate litigation attorney early — ideally before the will is admitted to probate, if the concern arises that soon — gives the contestant the most options for how to proceed.