A more thorough explanation:

A terrorem clause, also known as a no-contest clause, is a provision in a will that discourages beneficiaries from challenging the will's provisions. The clause imposes a condition on the beneficiary that they will not dispute the will's provisions. If the beneficiary violates the clause, they may lose their inheritance or interest in the estate.

For example, if a will includes a terrorem clause and a beneficiary challenges the will's validity, the clause may revoke their inheritance. However, the enforceability of terrorem clauses varies by jurisdiction and may be subject to strict construction.

In some states, such as New York, terrorem clauses that attempt to prevent a beneficiary from questioning the eligibility or conduct of a fiduciary will not be enforced because it goes against public policy. In Michigan, terrorem clauses are limited in power and may not be enforced if probable cause exists for instituting a proceeding contesting the trust or another proceeding relating to the trust.

Some jurisdictions have established a probable cause exception to terrorem clauses. For example, California courts may decline to enforce terrorem clauses where the beneficiary challenging the will acted in good faith and had probable cause for the challenge. Probable cause is defined as the existence of evidence that would lead a reasonable person to conclude that there is a substantial likelihood that the contest or attack will be successful.

In deciding the enforceability of terrorem clauses, courts will interpret the will as a whole to ascertain the intent of the testator. As a result, a challenge to a will, even in the face of a terrorem clause, will succeed if the challenge is consistent with the intent of the testator in drafting their will.