Undue influence occurs when one party exercises such control over a second party as to overcome the independent judgment and free will of the second party. In reviewing claims of undue influence, courts look to see whether the plaintiff preyed on and exploited a known psychological or physical weakness when securing the defendant’s assent to a contract. However, evidence that the plaintiff merely used aggressive and unsavory tactics in securing the defendant’s asset will not suffice to overturn a contract on grounds of undue influence, unless those tactics had the effect of substituting the plaintiff’s will and judgment for the defendant’s.