You set up a custody arrangement in court between you and the other parent. It is no longer working for you. You or the other parent moved out of D.C., the other parent doesn’t have a safe environment for your child, the other parent is living with someone who is a bad influence…There are a variety of reasons that you could want to file for a change in the custody arrangement (also called a custody modification). The court will consider whether there has been a material and substantial change in circumstances and it is in the best interests of your child. There is no cut and dry case where the court will definitely decide in your favor that there should be a change in the arrangement. But you can advocate strongly for one. If the other parent has moved out of D.C. then you will likely be able to file for a custody modification in D.C. as long as you still live in D.C. If you move to a new state and want to have the case heard by a court in the new state then you can ask the D.C. court to decline jurisdiction before you can file the case in the new state.