Section 8-308 - Challenge after expiration of period for rescission(a) After the period for rescission under § 8-307 of this title has expired, a signatory of an acknowledgment of paternity or denial of paternity may commence a proceeding to challenge the acknowledgment or denial only: (1) On the basis of fraud, duress, or material mistake of fact; and(2) Within 2 years after the acknowledgment or denial is filed with the Office of Vital Statistics.(b) A party challenging an acknowledgment of paternity or denial of paternity has the burden of proof.74 Del. Laws, c. 136, § 1; 70 Del. Laws, c. 186, § 1.;