Family Code 3421: Home State and Fallback Jurisdiction Grounds

California Family Code Section 3421 sets the only conditions under which a California court can make an initial child custody decision. It gives the court four possible grounds for jurisdiction, and those grounds apply in a strict order of priority. If a higher-ranked ground fits the facts, the lower ones do not come into play.¹

The statute is California’s version of Section 201 of the Uniform Child Custody Jurisdiction and Enforcement Act, a model law adopted to keep two states from issuing conflicting custody orders and to discourage parents from moving a child in search of a friendlier court.

Home State Jurisdiction Comes First

The primary basis, under subdivision (a)(1), is home state jurisdiction. A California court has authority if California is the child’s home state on the date the case is filed, or if California was the child’s home state within the six months before filing, the child is no longer in California, and at least one parent still lives here.¹

“Home state” has a fixed meaning. Under Family Code Section 3402, it is the state where the child lived with a parent or a person acting as a parent for at least six consecutive months immediately before the case was filed. For a child under six months old, it is the state where the child has lived since birth. Short trips out of state count toward the six-month period rather than resetting it.²

The six-month lookback exists to protect a parent left behind when the other parent takes the child out of state. If California was the home state when the child left, the remaining parent can still file here for six months after the departure.³

The Three Fallback Grounds

Significant Connection

Under subdivision (a)(2), a California court can take a case when no other state qualifies as the home state, or when the home state court has declined to hear it, provided two things are true: the child and at least one parent have a significant connection with California beyond simply being present here, and substantial evidence about the child’s care, protection, training, and personal relationships is available in the state.¹ This ground cannot be used to push aside a home state that wants the case.

Declined Jurisdiction

Subdivision (a)(3) applies when every court that would otherwise have jurisdiction under the first two grounds has declined to exercise it, finding that California is the more appropriate forum under the inconvenient-forum or unjustifiable-conduct provisions in Sections 3427 and 3428.⁴

Vacuum Jurisdiction

Subdivision (a)(4) is the catch-all. A California court can take the case if no court in any other state would have jurisdiction under any of the first three grounds.¹ This can happen when a child has moved so often that no state qualifies as the home state and no state has a significant connection.

How Jurisdiction Cannot Be Created

Section 3421 also spells out what does not produce jurisdiction. Subdivision (b) makes the four grounds in subdivision (a) the exclusive basis for a California court to make a custody determination. A court cannot rely on some other theory, such as a parent’s residence or the convenience of the forum.¹

Subdivision (c) states that the physical presence of a child or a parent in California, or personal jurisdiction over a party, is neither necessary nor sufficient by itself. A California court can make a custody order affecting an out-of-state parent, and being in California does not on its own give the court authority.¹

The parties also cannot manufacture jurisdiction by agreement. In In re Marriage of Nurie (2009), the California Court of Appeal held that even when both parents consent to California jurisdiction, a court that does not meet the statutory criteria has no authority to proceed.⁵ Waiver and estoppel do not fill the gap either.

Emergency Jurisdiction Is a Separate Track

Section 3424 creates a narrow exception. A California court may take temporary emergency jurisdiction if the child is physically present in California and has been abandoned, or if an emergency requires protecting the child, a sibling, or a parent from actual or threatened mistreatment or abuse.⁶

An emergency order is meant to be short-lived. When a custody case or order already exists in another state, the California order must set a period long enough for the protected person to get an order from the state with primary jurisdiction, and it expires when that period ends or the other state acts. If no prior order or proceeding exists anywhere else and no other state steps in, the emergency order can ripen into a final determination once California becomes the child’s home state.⁷ The California court is required to communicate immediately with any other court that has jurisdiction or has a pending case.⁸

What Happens After the Initial Order

Once a California court has made an initial custody determination under Section 3421, it keeps exclusive continuing jurisdiction under Section 3422. No other state can modify the order while California retains that authority. California loses continuing jurisdiction only if a court finds that neither the child nor a parent has a significant connection with the state and substantial evidence about the child is no longer available here, or if the child and all parents have left California.⁹

That loss requires an actual judicial finding. In Nurie, the court held that exclusive continuing jurisdiction is not self-terminating just because the parties have moved; a court has to determine that the statutory conditions are met.⁵

To modify an order originally issued by another state, Section 3423 requires two things: California must independently qualify for jurisdiction under Section 3421(a)(1) or (a)(2), and either the original state must find it no longer has continuing jurisdiction or that California is the more convenient forum, or a court must find that the child and parents no longer live in the original state.¹⁰

When a Court With Jurisdiction Declines to Use It

Having jurisdiction does not force a court to keep the case. Under Section 3427, a court that finds California is an inconvenient forum may stay the proceedings and send the parties to a more appropriate state. The court weighs factors including any history of domestic violence and which state can better protect the parties, how long the child has lived outside California, the distance between courts, financial hardship, where the evidence is, and each court’s familiarity with the case.¹¹

Section 3428 covers cases where California only has jurisdiction because a party engaged in unjustifiable conduct, such as wrongfully removing the child from another state. The court generally must decline to hear the case and may charge that party with the other side’s attorney’s fees and costs. Exceptions apply when all parties consent, when the other state defers to California, or when no other state has jurisdiction. Fleeing domestic violence, or seeking gender-affirming care for a child, is not treated as unjustifiable conduct.¹²

The Gender-Affirming Care Provision

Senate Bill 107, signed by Governor Gavin Newsom in 2022, added subdivision (d) to Section 3421 and amended several related statutes effective January 1, 2023.¹³ The law was written to make California a refuge for families from states that restrict or criminalize gender-affirming health care for minors.¹⁴

Subdivision (d) provides that a child’s presence in California to obtain gender-affirming health care or gender-affirming mental health care is by itself enough to satisfy the significant-connection and substantial-evidence requirements of subdivision (a)(2).¹ SB 107 also amended Section 3424 so that California courts can exercise temporary emergency jurisdiction when a child present in the state has been unable to obtain gender-affirming care elsewhere, and it added Section 3453.5, which declares that any other state’s law authorizing the removal of a child from a parent for allowing the child to receive gender-affirming care is against California public policy and will not be enforced.¹⁵

How Federal Law Constrains Section 3421

The federal Parental Kidnapping Prevention Act, 28 U.S.C. § 1738A, sits above every state custody-jurisdiction statute under the Supremacy Clause. The PKPA requires every state to give full faith and credit to custody orders from other states, but only when those orders were issued in compliance with the PKPA’s own jurisdictional standards. The UCCJEA was written to line up with the PKPA, so the two usually produce the same result. Where they diverge, the PKPA controls, and a custody order that violates it is not entitled to interstate recognition even if it satisfies California law.¹⁶

1
FindLaw. California Family Code Section 3421
2
Justia. California Family Code Sections 3400-3412
3
Office of Juvenile Justice and Delinquency Prevention. Uniform Child-Custody Jurisdiction and Enforcement Act
4
Justia. California Family Code Sections 3421-3430
5
CaseMine. In re Marriage of Nurie, 176 Cal.App.4th 478
6
FindLaw. California Family Code Section 3424
7
Justia. California Family Code Section 3424
8
California Courts. Bench Guide on UCCJEA Jurisdiction
9
FindLaw. California Family Code Section 3422
10
FindLaw. California Family Code Section 3423
11
FindLaw. California Family Code Section 3427
12
FindLaw. California Family Code Section 3428
13
Justia. California Family Code Section 3421
14
California Courts. Implementation of SB 107
15
California Courts. Invitation to Comment on SB 107 Implementation
16
American Academy of Matrimonial Lawyers. UCCJEA and PKPA Jurisdictional Analysis