CO Code § 14-5-315 (2021)
2021 Colorado Code|Title 14 - Domestic Matters|Article 5 - Uniform Interstate Family Support Act|Part 3 - Civil Provisions of General Application|§ 14-5-315. Nonparentage as Defense

 A party whose parentage of a child has been previously determined by or pursuant to law may not plead nonparentage as a defense to a proceeding under this article.   History. Source: L. 93: Entire article R&RE, p. 1593, § 1, effective January 1, 1995.    Editor's note:   This section is similar to former § 14-5-128 as it existed prior to 1993.   COMMENT   Arguably this section does no more than restate the basic principle of res judicata. However, there is a great variety of state law regarding presumptions of parentage and available defenses after a prior determination of parentage. As long as a proceeding is brought in an appropriate forum, this section is intended neither to discourage nor encourage collateral attacks in situations in which the law of another jurisdiction is at significant odds with local law. If a collateral attack on a parentage decree is permissible under the law of the issuing jurisdiction, such a proceeding must be pursued in that forum and not in a UIFSA proceeding.   This section mandates that a parentage decree rendered by another tribunal “pursuant to law” is not subject to collateral attack in a UIFSA proceeding. Of course, an attack on an alleged final order based on a fundamental constitutional defect in the parentage decree is permissible in the forum state. For example, a responding tribunal may find that another tribunal acted unconstitutionally by denying a party due process due to a failure of notice and opportunity to be heard or a lack of personal jurisdiction over a party who did not answer or appear. Insofar as the latter ground is concerned, the universal enactment of the long-arm statute asserting personal jurisdiction over a respondent if the child “may have been conceived” in the forum state may greatly reduce successful attacks on a parentage determination. Section 201(a)(6).  See  Similarly, the law of the issuing state or foreign country may provide for a determination of parentage based on certain specific acts of the obligor, such as voluntarily acknowledging parentage as a substitute for a decree. UIFSA also is neutral regarding a collateral attack on such a parentage determination filed in the issuing tribunal. In the meantime, however, the responding tribunal must give effect to such an act of acknowledgment of parentage if it is recognized as determinative in the issuing state or foreign country. The consistent theme is that a collateral attack on a parentage determination cannot be made in a UIFSA proceeding other than on fundamental due-process grounds.   ANNOTATION   Annotator's note: Since § 14-5-315 is similar to § 14-5-128 as it existed prior to the 1993 repeal and reenactment of this article, relevant cases construing that provision have been included in the annotations to this section.   Determination of paternity in divorce or annulment action. The parentage of a child is not an issue necessarily decided in a divorce or annulment action. However, where, as a part of a divorce action, the court hears evidence, makes a child support order, and by necessary implication has determined the paternity of the child, this determination is res judicata at least between the spouses. McNeece v. McNeece, 39 Colo. App. 160, 562 P.2d 767 (1977).   Applicability of doctrine of res judicata. Failure to raise the defense of nonpaternity during dissolution proceedings bars a presumed father from collaterally attacking the determination of paternity implicitly supporting award of child support incident to such dissolution proceedings brought under URESA. State ex rel. Daniels v. Daniels, 817 P.2d 632 (Colo. App. 1991).