State and national legal groups are trying to sway the Florida Supreme Court in a parental-rights case that pits two lesbian partners who used in vitro fertilization to have a child but later ended their relationship.

The Brevard County case is unprecedented in Florida because the fertilized egg of one woman was implanted in her then-partner, who gave birth. The couple began raising the child together, but a legal battle began after a breakup that included the birth mother moving to Australia with the child.