You don't need to throw the baby out with the bathwater. While many will contests challenge the validity of an entire will, others focus on one term. Some common legal grounds for challenging a will necessarily negate the entire document, but others — e.g., undue influence, forgery or fraud — may be limited to one late-added codicil. Like most contested litigation, will contests proceed in court following strict statutory procedures, and parties often choose to be represented by attorneys.
Review the will carefully to identify the objectionable provision. Note whether the decedent included the provision in the original will, or whether he added it later as a codicil.
Learn everything you can about wills and will contests in the jurisdiction in which the will is to be probated. Rules regarding standing to challenge a will and grounds for a will contest differ among states. Inform yourself using local law library facilities, court handouts, and any court self-help centers available to you. Address procedural questions to the court clerk.
Draft the initial document challenging the will provision. In some states this is called an objection, in others a challenge. Use correct terminology and file the paper in proper form. Most jurisdictions prescribe a limited window of time to file an objection; be sure your filing is timely. After you file the objection, the court will set a hearing date and inform you and all other interested parties of that date.
Gather evidence supporting your claim that the will provision is faulty or invalid. Talk to potential witnesses, investigate the circumstances, do all in your power to build a case that the provision in question should not be enforced.
Attend the trial or hearing on the contest of the will provision. Present your arguments and evidence. Explain clearly why the provision must fail while the rest of the will should be probated. Remember that the court can invalidate one provision or the entire will, and tailor your arguments to the result desired. The court may rule at the hearing or else may take the matter under advisement, issuing a written decision some days after the hearing.