Direct interest
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
A direct interest, such as would render the interested party incompetent to testify in regard to the matter, is an interest which is certain, and not contingent or doubtful. A matter which is dependent alone on the successful prosecution of an execution cannot be considered as uncertnin, or otherwise than direct, in this sense.
In re Van Alstine's Estate, 26 Utah, 193, 72 Pac. 942.