The two main challenges to a will are:

Lack of Testamentary Capacity 
The standard implement to testamentary capacity is:

  • Whether the testator can comprehend the property he is about to dispose of
  • The natural objects of his bounty
  • The meaning of the business in which he is engaged
  • The relation of each of factors to the others
  • The distribution that is made by the will.

Undue Influence 
A will that is a product of undue influence is void. Undue influence has been defined as “mental, moral or physical exertion, which has destroyed the free agency of the testator, by preventing a testator from following the dictates of his own mind and will and accepting instead the domination and influence of another.”