A will must clearly be the product of undue influence for a challenge to succeed. In its opinion in Burkhalter v. Burkhalter, 841 N.W.2d 93 (Iowa 2013), the Iowa Supreme Court thoroughly discusses the amount of evidence required to prove undue influence on a testator. While confirming the preponderance of the evidence standard, the court also confirms the existing rule that the will must “clearly” be the product of undue influence and states that such a requirement is not inconsistent with a preponderance standard.
Special thanks to William LaPiana (Professor of Law, New York Law School) for bringing this case to my attention.