McFarlin

Section 621 of the Evidence Code provides that “the issue of a wife cohabiting with her husband, who is not impotent or sterile, is conclusively presumed to be a child of the marriage” absent rebuttal by certain specified means within two years of the child’s birth. The sole issue before us is whether the trial court’s application of this presumption was unconstitutional in this case. We conclude that it was, and accordingly reverse the trial court’s order of paternity.

*1084 Factual Background

The essential facts are undisputed. Rita de L. has five minor children. The oldest three, Lenora, Eugene and James, are the children of respondent Fermín G., Rita’s ex-husband, and now live with him. Melissa, the fourth child, was born eight days prior to Rita and Fermin’s separation in August 1983. Fermín was listed on the birth certificate as Melissa’s father and Melissa was named as a child of the marriage in Rita and Fermin’s dissolution. Rita told a social worker, however, that appellant Felix de L. was Melissa’s father.

In December 1983 Rita and Felix began living together and in August 1984 they married. Their daughter, Shannon, was born in February 1985. Between August…