The first thing that the judge would look at is what sort of formal custody order is in place. Do you have sole physical custody or not and if there has never been a formal custody order, the court would decide what the informal custody order is. Assuming you have sole physical custody of the child, that is a so called “real advantage test” this is whether or not there is a real advantage to your move and secondly whether that move is in the best interest of the child.
It is under a case called Yannas and the judge will want to look at a lot of factors including why you want to move, for example is there a good sincere reason why you are looking to do that and will your move benefit you and your child emotionally, economically and socially, if the move is good for you, they consider that a real advantage test. The judge will assume that the move is good for the child.
The court will also look to make sure that you are not moving to keep the other parents from seeing the child. The judge needs to know the reasoning is not to keep the other parent from seeing the child and if he/she believes that is the reason and will not allow that to occur. The judge then decides after the real advantage test that you have a good sincere reason to move, then he/she will balance both parents and the child to determine whether it is in the child’s best interest or not.
For example, what is called a per se rule under the real advantage is you can relocate with a new spouse and in of itself should be considered a good enough reason legally to move. Under this sincere reason, it can still be outweighed by some other factors under Yannas.