Legal custody is best thought of as decision-making for the children and is different from physical custody.  

It is resolution of how major decisions affecting the welfare of the children are made, such as medical decisions (i.e. elective surgeries, whether to start therapy, getting vaccines, etc.), educational decisions (such as what school to attend), major changes of appearance (such as piercings and tattoos), changes regarding daycare/child care, etc. I have a separate post that addresses Physical Custody, which I would encourage you to read.

“Joint legal custody” is joint decision-making authority.  It means that you are supposed to make decisions similarly to how you would hopefully have made them prior to separation – by discussing them and trying to reach a mutual agreement.  If you don’t agree, then technically neither of you has the authority to overrule the other, unless the judge has granted final decision-making authority.  The vast majority of parents will receive joint legal custody of their children.  I describe the cases in which a parent does not receive joint legal custody as those in which one parent is either unable (severe use of drugs or alcohol, severe psychological impairment, etc.) or unwilling to participate in decision-making for the children.  In those cases, a parent can be granted “sole legal custody,” which means that they may not even have to discuss such matters with the other parent prior to making a decision.  Sole legal custody is rare.  You are likely to share joint legal custody with the other parent unless you can present very compelling evidence that even having to discuss the children’s issues with the other parent is not in the children’s best interests. 

“Final decision-making authority” is a something that a party can be granted to break a tie when parties with joint legal custody are unable to agree.  Most often, when a parent tells me they want sole legal custody, what they are really going to be arguing for is having the final decision-making authority.  A judge does not have to grant either parent final decision-making authority.  They can essentially make the parents come back to Court if a decision must be made and the parties cannot agree.  This authority can certainly be abused, especially when a parent with final decision-making authority acts as if they have sole legal custody, or when they think that it gives them the right to unilaterally override other provisions of the custody order.  Different judges have different views on whether a parent should be granted this authority.  Some take the view that at the end of the day someone has to be able to make the decision without coming back to Court every time, as some parents can find a way to disagree on anything, and everything.  Others take the view that the parents should have to agree and neither should have a superior authority to the other.  Whether either parent will be granted such authority will likely depend on the tendencies of your judge and the particular facts of your case.

In cases where the parents share 50/50 physical custody, or something close to it, it will be less likely that one parent will have final decision-making authority.  In cases where one parent is granted primary physical custody, there is a greater chance that the primary physical custodian will be awarded this authority.