Sole legal custody refers to a custody agreement in which one parent has full custodial rights over a child or chidren. This can happen for a number of reasons and is the opposite of joint custody or shared custody. It gives the parent the power to make all decisions regarding the child's education, medical, and legal issues.
Justipedia explains Sole Legal Custody
Sole legal custody can be awarded to either parent after a divorce action or separation. The term means that the parent is the only one who has responsibility over the children and is legally responsible for their upbringing and well-being.