When parents and children have connections to more than one state, a California family court cannot decide custody simply because one parent files a case in California. Interstate child custody jurisdiction is governed by rules designed to determine which state has authority to make custody and visitation orders. One of the most important concepts is the child’s “home state,” although California may have jurisdiction on other grounds in certain circumstances.

The Child’s Home State Is Usually the Starting Point

For an initial California child custody determination, an important question is whether California is the child’s home state when the custody proceeding begins.

Generally, a child’s home state is the state where the child lived with a parent or a person acting as a parent for at least the six consecutive months immediately before the custody proceeding began. For a child younger than six months, the analysis generally looks to where the child has lived from birth.

Temporary absences are counted as part of the relevant period.

California may also have home-state jurisdiction when California was the child’s home state within six months before the proceeding began, the child is currently outside California, and a parent or person acting as a parent continues to live in California.

That provision can be significant when one parent recently moved a child to another state. The child’s physical presence outside California on the filing date does not necessarily mean California immediately loses the ability to make the initial custody determination.

Other Jurisdictional Grounds May Apply When California Is Not the Home State

Home-state jurisdiction is not the only possible basis for an initial custody determination.

Under appropriate circumstances, California may exercise jurisdiction when no other state qualifies as the child’s home state, or when the home state declines jurisdiction because California is the more appropriate forum.

In that situation, the child and at least one parent or person acting as a parent must have a significant connection with California beyond mere physical presence. Substantial evidence concerning the child’s care, protection, training, and personal relationships must also be available in California.

Jurisdiction may also arise when courts that otherwise could exercise jurisdiction decline to do so because California is the more appropriate forum. California can also exercise jurisdiction when no other state qualifies under the applicable jurisdictional rules.

These rules demonstrate why interstate custody jurisdiction is different from simply asking where either parent currently lives.

The physical presence of the child in California is not, by itself, sufficient to establish ordinary custody jurisdiction. Likewise, California does not necessarily need personal jurisdiction over a parent to make a custody determination when jurisdiction and notice requirements are otherwise satisfied.

Temporary Emergency Jurisdiction Is Different From Ordinary Custody Jurisdiction

California can exercise temporary emergency jurisdiction in specific circumstances even when another state would ordinarily have jurisdiction.

For emergency jurisdiction to apply, the child must be present in California. The child must have been abandoned, or an emergency must make it necessary to protect the child because the child, a sibling, or a parent has been subjected to or threatened with mistreatment or abuse. California law also recognizes a specified basis involving a child’s inability to obtain qualifying gender-affirming health care or mental health care.

Emergency jurisdiction is temporary and should not be confused with ordinary home-state jurisdiction.

If another state already has an enforceable custody determination or a custody proceeding is pending in a state with jurisdiction, a California emergency order must generally provide an appropriate period for the person seeking protection to obtain an order from that state. California and the other state’s court must also communicate when the applicable circumstances require it.

Temporary emergency jurisdiction does not automatically turn into permanent California jurisdiction merely because no one immediately starts another proceeding. Whether an emergency determination can ultimately become final depends on the specific jurisdictional circumstances and requirements.

Interstate Custody Starts With Jurisdiction

Before a California family court decides what custody arrangement is in a child’s best interests, it must first have authority to make that decision. The child’s home state is often the starting point, but significant connections, proceedings in another state, and genuine emergencies can affect the analysis. Temporary emergency jurisdiction is particularly important to distinguish from ordinary custody jurisdiction because an emergency order does not automatically give California permanent authority over the custody case.