C.R.S. § 19-4-105. Presumption of paternity.
(1) A man is presumed to be the natural father of a child if:
(a) He and the child’s natural mother are or have been married to each other and the child is born during the marriage, within three hundred days after the marriage is terminated by death, annulment, declaration of invalidity of marriage, dissolution of marriage, or divorce, or after a decree of legal separation is entered by a court;
(b) Before the child’s birth, he and the child’s natural mother have attempted to marry each other by a marriage solemnized in apparent compliance with law, although the attempted marriage is or could be declared invalid, and:
(I) If the attempted marriage could be declared invalid only by a court, the child is born during the attempted marriage or within three hundred days after its termination by death, annulment, declaration of invalidity of marriage, dissolution of marriage, or divorce; or
(II) If the attempted marriage is invalid without a court order, the child is born within three hundred days after the termination of cohabitation;
(c) After the child’s birth, he and the child’s natural mother have married, or attempted to marry, each other by a marriage solemnized in apparent compliance with law, although the attempted marriage is or could be declared invalid, and:
(I) He has acknowledged his paternity of the child in writing filed with the court or registrar of vital statistics, if such acknowledgment has not previously become a legal finding pursuant to paragraph (b) of subsection (2) of this section;
(II) With his consent, he is named as the child’s father on the child’s birth certificate; or
(III) He is obligated to support the child under a written voluntary promise or by court order or by an administrative order issued pursuant to section 26-13.5-110, C.R.S.;
(d) While the child is under the age of majority, he receives the child into his home and openly holds out the child as his natural child;
(e) He acknowledges his paternity of the child in a writing filed with the court or registrar of vital statistics, which shall promptly inform the mother of the filing of the acknowledgment, and she does not dispute the acknowledgment within a reasonable time after being informed thereof, in a writing filed with the court or registrar of vital statistics, if such acknowledgment has not previously become a legal finding pursuant to paragraph (b) of subsection (2) of this section. If another man is presumed under this section to be the child’s father, acknowledgment may be effected only with the written consent of the presumed father or after the presumption has been rebutted.
(f) The genetic tests or other tests of inherited characteristics have been administered as provided in section 13-25-126, C.R.S., and the results show that the alleged father is not excluded as the probable father and that the probability of his parentage is ninety-seven percent or higher.
(a) A presumption under this section may be rebutted in an appropriate action only by clear and convincing evidence. If two or more presumptions arise which conflict with each other, the presumption which on the facts is founded on the weightier considerations of policy and logic controls. The presumption is rebutted by a court decree establishing paternity of the child by another man. In determining which of two or more conflicting presumptions should control, based upon the weightier considerations of policy and logic, the judge or magistrate shall consider all pertinent factors, including but not limited to the following:
(I) The length of time between the proceeding to determine parentage and the time that the presumed father was placed on notice that he might not be the genetic father;
(II) The length of time during which the presumed father has assumed the role of father of the child;
(III) The facts surrounding the presumed father’s discovery of his possible nonpaternity;
(IV) The nature of the father-child relationship;
(V) The age of the child;
(VI) The relationship of the child to any presumed father or fathers;
(VII) The extent to which the passage of time reduces the chances of establishing the paternity of another man and a child support obligation in favor of the child; and
(VIII) Any other factors that may affect the equities arising from the disruption of the father-child relationship between the child and the presumed father or fathers or the chance of other harm to the child.
(b) A duly executed voluntary acknowledgment of paternity shall be considered a legal finding of paternity on the earlier of:
(I) Sixty days after execution of such acknowledgment; or
(II) On the date of any administrative or judicial proceeding pursuant to this article or any administrative or judicial proceeding concerning the support of a child to which the signatory is a party.
(c) Except as otherwise provided in section 19-4-107.3, a legal finding of paternity may be challenged in court only on the basis of fraud, duress, or mistake of material fact, with the burden of proof upon the challenger. Any legal responsibilities resulting from signing an acknowledgment of paternity, including child support obligations, shall continue during any challenge to the finding of paternity, except for good cause shown.