Legal Question in Family Law in California

No. A parent with physical custody of a child is not legally obligated to turn the child over to the other parent until there is an order in place. The only warning I have is that refusing to let the other parent have custodial time with the child, prior to the hearing on the order, can be used against that parent in custody proceedings. It is the public policy of the state that children have regular and continuing time with each parent unless there are sound reasons to the contrary. The mother's threat to keep the child away from the father, may be a good enough reason/explaination for the court, but if the court finds that the mother didn't actually make that threat, or if the court finds the threat wasn't really plausible under all the facts and circumstances, preventing the mother from having time with the child could backfire for the father.