Can my father contest the terms of my grandfather's trust if there is a no-contest clause in it?
Someone needs valid grounds to successfully challenge a trust, but that doesn't stop a person who stands to gain if he or she can overturn the trust (in whole or in part) from trying to do it. If your father has his father’s trust invalidated, he may receive more property under his father’s will or under your state’s laws of intestate succession (laws that say who gets property when someone dies without a will) than he receives under the trust.
The usual reasons for challenging a trust are lack of mental capacity, fraud, mistake, undue influence, and duress. Your father would have to show that your grandfather was incompetent when he made the trust, that he made a mistake, or that someone else was defrauding, influencing, or forcing him. The trust might also be overturned if it was not created properly under the laws of the state where your grandfather set it up.
It isn’t easy to successfully challenge a trust, but because such challenges are very expensive and can eat up all the assets of a trust in legal expenses, the other beneficiaries are sometimes willing to settle the dispute to preserve the estate. A no-contest clause doesn’t stop someone from challenging a trust. It only means that if the person does challenge it and fails, he or she will receive nothing under the trust. If your father wasn’t going to receive anything under the trust anyway, a no-contest clause wouldn’t affect him at all.