One of the most common reasons that people challenge a will or other estate plan documents after a person's death is "undue influence." This is when someone coerces (mentally, physically and/or morally) a testator to the point where that person isn't designating the dispersion of their assets as they would if they were exercising their own free will.
Not all influence is "undue." For example, a wife may talk her husband into agreeing to disburse their assets among their children in a different way than he originally planned to. That's not considered the kind of coercion or domination that characterizes undue influence.
It's generally the responsibility of the plaintiffs (those alleging undue influence by the executor or others) to prove that allegation. They have the burden of proof.
There are some circumstances in which the will's proponent (the person who "offers it for probate") has the burden of proof to show that it was drafted without undue influence. This may happen if there are suspicious circumstances around the execution of the documents or if the relationship between the alleged influence and the testator was confidential. A confidential relationship could be between an attorney and client or even a child and parent.
No reasonable person wants their family or others fighting over their estate after they're gone. It's an expensive, time-consuming and often ugly process that can rip families apart at a time when they often need each other's support the most. There are steps that you can take while you're creating your estate plan, such as discussing some of your provisions and the reasoning behind them, with those impacted -- particularly if you think they might not be well-received by loved ones.
North Carolina estate planning attorneys can help you work to minimize the chances of a court battle over your estate. They can also provide guidance in creating an estate plan that meets your goals and needs.