What are the most important Washington de facto parentage cases?

The most important Washington cases to understand de facto parentage begin with In re Parentage of L.B., 155 Wn.2d 679, 122 P.3d 161 (2005), the Washington Supreme Court’s landmark decision that recognized de facto parentage under common law. That case established the original four-part test for recognizing a de facto parent and remains the foundation for all subsequent decisions. The next key decisions further refine application of the doctrine, especially as codified in Washington’s Uniform Parentage Act, RCW 26.26A.440.

1. In re Parentage of L.B. (2005)

Issue: Whether a same-sex partner who jointly planned and raised a child with the biological parent could be recognized as a de facto parent.

Holding: Yes. The Washington Supreme Court formally adopted the de facto parentage doctrine as an equitable remedy to bridge statutory gaps for those who function as parents in every sense except biology or adoption. The court identified four elements: (1) consent and fostering by a legal parent, (2) co-residence, (3) assumption of full parental responsibilities without financial compensation, and (4) an established bonded, dependent relationship parental in nature.[1]

2. In re Custody of B.M.H., 179 Wn.2d 224, 315 P.3d 470 (2013)

Issue: Whether a former stepfather could be recognized as a de facto parent despite not being biologically related and despite opposition from the biological parent.

Holding: The Washington Supreme Court held that a former stepfather who had acted as a parent with the consent and encouragement of the child’s mother could pursue de facto parentage. This case extended L.B. to heterosexual stepparent contexts and reaffirmed that de facto parentage protects the child’s established family relationships consistent with the child’s best interests and due process rights of the legal parent.[2]

3. In re Parentage of M.F., 168 Wn.2d 528, 228 P.3d 1270 (2010) (also known as Corbin v. Reimen)

Issue: Whether an ex-stepfather who co-parented a child for over a decade could claim de facto parent status.

Holding: The court denied standing, finding insufficient evidence that the biological mother had fostered and consented to a permanent parent-like relationship. This case clarified the essential requirement of the legal parent's consent in establishing de facto parentage and highlighted constitutional constraints following Troxel v. Granville, 530 U.S. 57 (2000).[2]

4. In re Parentage of J.L., No. 38579-5-III (Wash. Ct. App. Sept. 22, 2022) (unpublished)

Issue: Whether grandparents who had assumed long-term parental duties could proceed with a de facto parentage petition under Washington’s 2019 UPA revisions.

Holding: The Washington Court of Appeals allowed the claim to proceed, emphasizing that the petition met preliminary sufficiency standards for trial under the statutory framework of RCW 26.26A.440. The court reaffirmed that L.B.’s equitable criteria now appear codified as statutory elements.[1]

5. Statutory codification: RCW 26.26A.440

In 2019, Washington adopted its updated Uniform Parentage Act, explicitly establishing a process to adjudicate de facto parentage. Section .440 sets seven statutory requirements mirroring those from L.B., including consistent caregiving, residence with the child, assumption of full parental responsibility, recognition of the child as one’s own, and the legal parent’s fostering of that relationship.[3]

Summary Table

Together, these cases trace the evolution of de facto parentage in Washington from an equitable common-law remedy to a statutory recognition protecting both children’s relationships and constitutional parental rights.