Most wills have a no contest clause in them. These no contest clauses are also called in terrorem clauses. I have described these here. Many people ask if these no contest clauses mean that they can't contest a will. The answer to that question is no.
Courts are reluctant to enforce these clauses because of the chilling effect they have on legitimate claims that the will being contested is not the will of the testator. Imagine a situation where a person has gained undue influence over the testator who then makes a will leaving little to his family and benefiting the person exerting the undue influence. If the family receives anything under the will, they will be afraid that they will lose what little they have if they contest the will. It's for this reason that court's are reluctant to enforce these clauses. The legislature also passed a law making these provisions void if the person contesting the will did so in good faith and with just cause. Under that law, even if a contestant loses the will contest, he won't be denied his inheritance set out in the unsuccessfully challenged will if the court or jury finds he was contesting the will in good faith and with just cause. Of course, if someone is contesting a will without good faith and just cause, the courts may enforce the no contest clause. There are very few cases where the courts have enforced these provisions although there are some.