Legal Question in Family Law in California

If your son has lived in Michigan for more than six months, then California no longer has jurisdiction and you will have to file a motion for a custody change in Michigan.

With all due respect to Ms. Kadeg, she should contact her malpractice carrier if she is so willing to answer questions when she has no clue as to the right answer. Once a state has jurisdiction over the minor child in a custody proceeding that state has continuing jurisdiction until the emancipation of the child unless that court agrees to abstain and transfer the case to the state of the child's new residence, AND if and ONLY if both parents have left the state of original jurisdiction. Furthermore, not only does jurisdiction continue until the case is sent elsewhere, the LAW of the original state remains in effect as to the case. (This can be a big deal when one state requires support through college (e.g. NJ) and another does not (e.g. CA)). So although in your situation California COULD surrender jurisdiction, until the California court is asked to, AND agrees to, transfer the case to Michigan, California has sole jurisdiction.

Now, with that cleared up, the California court is obligated to order custody and a visitation schedule that will be "in the best interest of the minor child." So "will" a CA judge allow custody outside the US? The only possible answer is "maybe." It is up to you to show the judge that it is in the best interests of the minor child to live in Costa Rica with you, and to demonstrate that allowing the child to go outside U.S. jurisdiction does not pose a threat of parent abduction. I'm pretty sure Costa Rica has very cooperative extradition relations with the US. So that would be one important point to confirm and include in your case. At 15 the wishes of the child will be given meaningful evidentiary weight on the issue of best interests. You'll want to demonstrate how he will get an equal education, and superior cultrual and personal growth opportunities by living overseas. Other than that, you just need to make your best case that he will most benefit from being with you.