Legal Question in Family Law in Illinois

If you are over the age of majority or are otherwise an emancipated minor and you are under no other legal disability, no court needs to be involved. If there is a court order affecting your parental rights or obligations, such as a divorce decree that grants your ex- various rights like visitation, then yes because you could be prejudicing your ex's rights. Then again the divorce decree may grant certain kinds of permissions. So the first thing to do is identify what the court situation is, and by the sound of it you should see a lawyer to help identify your rights and obligations. There just aren't enough facts here and by the sound of it there's more to the situation.

You can lose custody of the child, or be ordered to return to IL (if you want to keep the child). You can't just leave the state and essentially screw over the other parent without court permission.