When parents and children live in different states, filing first in California does not necessarily give a California court authority to decide custody. Interstate custody jurisdiction is governed by a uniform framework intended to prevent conflicting orders and discourage parents from relocating children to obtain a preferred forum.

The jurisdictional analysis must occur before the court decides which parenting arrangement serves the child’s best interests.

The Child’s Home State Is Usually Central

For an initial custody determination, the court generally examines where the child lived with a parent or person acting as a parent during the relevant period before the case began.

Temporary absences do not necessarily interrupt the home-state period. A recent move may therefore leave the prior state with priority even though the child is physically present in California when the petition is filed.

The court may need information about residences, schools, caregivers, custody proceedings, and prior orders. Parents are expected to disclose other custody cases and proceedings that could affect jurisdiction.

A court should not decide the merits merely because one parent and child are currently within its borders.

An Existing Order Changes the Analysis

When another state has already entered a custody order, the issuing state may retain authority to modify it.

Moving to California does not automatically transfer modification jurisdiction. The analysis can depend on whether the child, parents, or persons acting as parents still have meaningful connections with the issuing state and where substantial evidence concerning the child remains available.

California may sometimes enforce an out-of-state order without having authority to modify it. Enforcement requires compliance with the existing terms; modification changes those terms. The two forms of relief should not be treated as interchangeable.

A parent should not violate the existing order based on the belief that California will eventually assume jurisdiction.

Emergency Jurisdiction Has a Narrower Purpose

A California court may have temporary emergency authority when a child is present in California and immediate protection is required because the child, a sibling, or a parent faces mistreatment, abuse, or a qualifying threat.

Emergency jurisdiction is not simply an alternative to ordinary home-state jurisdiction. Its purpose is immediate protection, and the resulting order may be temporary.

If another state has an existing custody order or an active proceeding, the courts may need to communicate and coordinate. The emergency order should identify its duration and relationship to proceedings in the state with ordinary jurisdiction.

A routine scheduling disagreement or preference to litigate in California does not create emergency authority.

Jurisdiction and Best Interests Are Separate Questions

Evidence showing that a proposed California parenting plan would benefit the child does not itself establish jurisdiction.

The court must first determine whether California has authority to make the requested initial or modified order. Only then does it apply the custody standards governing the merits.

Likewise, jurisdiction does not guarantee a particular custody result. It identifies which court may decide, not which parent should prevail.

Complete Interstate Information Prevents Conflicting Orders

Parents should provide every existing custody order, the child’s residential history, information about pending cases, and facts concerning any emergency.

A parent who seeks enforcement should identify the exact provision violated. A parent seeking modification should explain why California may now exercise modification jurisdiction rather than assuming residency alone is sufficient.

Interstate custody law protects stability by assigning decision-making authority to the proper court. Distinguishing initial jurisdiction, enforcement, modification, and temporary emergency protection helps prevent overlapping orders while preserving prompt relief when a child faces immediate danger.