A no-contest or in terrorem clause in a will or a trust typically makes the gifts in the instrument conditional on the beneficiary not challenging or disputing the validity of the instrument. The term in terrorem, as applied to wills, refers to a gift given on the condition that the beneficiary will not dispute the validity or disposition of the will.

In terrorem clauses are designed to dissuade beneficiaries from filing vexatious litigation that might thwart the intent of the testator (person who made the will) or the grantor or settlor (person who created the trust).

In terrorem clauses allow the intent of the testator to be given full effect and avoid vexatious litigation—often among members of the same family. If the intention of a suit is to thwart the settlor's intention, the in terrorem clause should be enforced. Laws vary from state to state but a violation of the in terrorem clause will usually be found only when the acts of the parties clearly fall within its express terms. Thus, many courts narrowly construe in terrorem clauses to avoid forfeiture, while also fulfilling the settlor's intent.

And some courts have held that filing suit to determine a testator's intent, or to ascertain a beneficiary's interest under a will, is not a suit intended to dispute the validity of the will. A suit brought in good faith and upon probable cause, to ascertain the real purpose and intention of the testator and to then enforce such purpose and intention, is not an effort to vary the purpose and intention of the will.

These courts reason that a motion to contest a will is, like any other motion, merely a pleading that is the necessary vehicle by which the movant raises issues for resolution. A motion is not self-proving. If the mere filing of a motion to contest a will is a contest of the will, this would be inconsistent with the legal significance of a motion.

In states whose courts follow this reasoning, unless some further action is taken to thwart the intention of the testator, the mere filing of a contest motion is insufficient to cause a forfeiture under an in terrorem clause.

In Oregon, a no-contest or in terrorem clause in a will or trust is generally enforceable. These clauses are intended to prevent beneficiaries from challenging the validity of the document and to uphold the intent of the person who created the will (testator) or trust (settlor). Oregon law recognizes the validity of in terrorem clauses but also acknowledges that there are circumstances under which a beneficiary may have a legitimate reason to challenge a will or trust. For instance, if a beneficiary has probable cause and is acting in good faith, a challenge may not necessarily trigger the in terrorem clause. This means that if a beneficiary is genuinely seeking to understand the testator's intent or to clarify their interest under the will, and not to disrupt the testator's wishes, the clause might not be enforced. However, if a challenge is deemed to be vexatious or without probable cause, and it appears to be an attempt to thwart the settlor's intention, the in terrorem clause could result in the forfeiture of the beneficiary's interest as outlined in the will or trust. It's important for beneficiaries in Oregon to consider the potential consequences of challenging a will or trust that contains an in terrorem clause and to seek the advice of an attorney before taking any action that could be construed as a contest.