Generally speaking, it's not easy to get a court to rule a will is invalid. For the most part, as long as the will follows all the formal requirements, a court is likely to find it is enforceable.
However, there are times when interested parties have reason to believe the will does not represent the actual wishes of the departed. These parties can contest the will, arguing that it is invalid. In many cases, relatives of the deceased argue that the will is not valid because it is the product of fraud, forgery or undue influence.
The question of undue influence comes up often in cases alleging that someone manipulated or pressured the deceased to give all or most of their property to them when they died. These can be emotionally difficult and legally complex cases, and should be handled by an attorney with experience in probate litigation.
To successfully challenge a will on the basis of undue influence, you must show that the testator, the person who created the will, did not create it out of free will, but was rather manipulated into it. Generally, this means having to show that the testator was susceptible to undue influence. For example, evidence that the testator suffered from dementia could help show that the testator was susceptible to manipulation.
Further, the person challenging the will must typically show that the alleged manipulator had the opportunity and disposition to pressure the testator. Perhaps most difficult of all, challenging the will requires showing that the will would not have been made had it not been for the improper influence.
These elements are not easy to prove. A skilled probate litigation attorney can help concerned people understand their legal options and the evidence they will need to successfully challenge a will.