To prove undue influence, a contestant generally must show that influence was exerted on the testator, that the influence overcame the testator's free will, and that the resulting will reflects the effect of that influence rather than the testator's independent intent — courts distinguish undue influence from ordinary persuasion, affection, or even aggressive advocacy for a particular bequest, all of which are permissible. Direct evidence of coercion is rare, so courts frequently rely on circumstantial factors instead.

Common circumstantial factors include a confidential or fiduciary relationship between the testator and the alleged influencer, the influencer's active participation in procuring or drafting the will, unusually secretive circumstances surrounding execution, a significant and unexplained departure from the testator's prior estate plan or previously expressed wishes, and the testator's physical or mental vulnerability at the time. Many states apply a rebuttable presumption of undue influence when a confidential relationship exists and the influencer received an unnatural or disproportionate benefit, shifting the burden to the beneficiary to explain the bequest.

Because undue influence findings rest heavily on a constellation of circumstantial facts rather than a single dispositive fact, Juricratic models it as a composite dial built from the individually weighted circumstantial factors a user inputs, rather than a binary yes-or-no prediction.

Estate litigators build undue influence cases around the relationship dynamics leading up to execution — who arranged the attorney meeting, who was present, how the new plan departs from prior wills — because the presence of a confidential relationship plus active procurement is often what shifts the practical burden of proof, even without direct evidence of coercion.