The best type of lawyer for this sort of case is someone who is experienced in trying civil lawsuits. A will contest is typically tried and decided by a jury, so you want a lawyer who is comfortable picking a jury and presenting evidence to twelve strangers who do not know you or the sister. Find out how much experience the lawyer has actually trying cases before a jury before hiring him or her.
There are a number of other ways that wills are attacked but here are the most common types of challenges:
1. The Testator (your best friend) lacked mental capacity to make and execute a will; or,
2. The will was procured by the exercise of undue influence, or,
3. The will was procured by duress.
Lack of capacity may be inferred from the fact that the person is old, is feeble, is eccentric, is intellectually weak, or is physically infirm. Often medical testimony is used to prove the existence of lack of testamentary capacity. There is an inference that the testator did have capacity to make a will if a lawyer drafted and supervised its execution.
Undue influence occurs when a person's professed act is not his own, but is in fact the act of the person exerting the influence. Influence is undue when it causes a person to make a will which he would not have otherwise made. The undue influence must act upon the free will of the person at the time he executes his will.
Duress occurs when a wrongful act, threat or coercion is used to force a person to make a will he would not have otherwise made. An extreme example of this would be someone signing a will with a gun pointed to his head.
I hope this helps. Please feel free to contact me if you have further questions.
Answered on Mar 15th, 2016 at 9:28 AM