Generally, only a person with a direct interest in the outcome — a named beneficiary, a former beneficiary who was removed in a later amendment, or someone who would have inherited under intestacy or a prior estate plan — has standing to contest a trust. Someone with no legal or financial stake in the trust typically cannot challenge it, even if they disagree with its terms.

Because trusts are often amended multiple times over a person's life, a contest may focus on a specific amendment rather than the entire trust — for example, arguing that a later amendment made while the person's capacity was in decline should be set aside while earlier, valid versions of the trust remain in effect.

The most frequently raised grounds include lack of mental capacity at the time the trust or an amendment was created or signed, undue influence by someone with a close relationship to the person who benefited from the change, fraud or misrepresentation, and improper execution that failed to follow the state's legal formalities for creating or amending a trust.

Because these grounds are fact-intensive, evidence like medical records, communications close in time to the trust's creation or amendment, and testimony from people who interacted with the settlor around that period often becomes central to the dispute.

Wills are validated through the probate court, which creates a formal, public process for challenging them. Trusts, by contrast, are often administered privately by a trustee without automatic court oversight, so a beneficiary who wants to contest a trust frequently has to initiate a separate court action rather than raising the challenge inside an existing probate proceeding.

Some trusts include a 'no-contest' or 'in terrorem' clause, which can reduce or eliminate a beneficiary's inheritance if they challenge the trust and lose. Whether these clauses are enforceable, and under what circumstances, varies by state, so understanding the specific trust's language and the relevant state law is an important early step before filing a contest.

Because trust litigation can be expensive, time-consuming, and — if a no-contest clause applies — risky to the person's own inheritance, it is worth evaluating the strength of the evidence and the potential outcome before filing. An attorney experienced in trust litigation can assess whether the available evidence realistically supports a claim like undue influence or lack of capacity.

Trustees also owe fiduciary duties to beneficiaries independent of the trust's validity — mismanagement, self-dealing, or failure to account can be challenged separately from a contest over whether the trust itself is valid, and sometimes that is the more direct path to relief.