A system for controlling a blowout preventer stack and subsea test tree connected to a subsea wellhead assembly, the system comprising: a marine riser engageable with the subsea wellhead assembly; a lower marine riser package configured to be attached to the marine riser in the subsea environment, wherein the blowout preventer is configured to be removably attached to the lower marine riser package; an umbilical located outside of the marine riser adapted to communicate control fluids, electrical signals and/or fiber optic communications to a subsea controller, wherein the subsea controller is configured to receive control fluids and/or signals from the umbilical and to provide functions to the blowout preventer stack and subsea test tree, further wherein the subsea controller stabs into the system above the subsea wellhead assembly. This out-of-marine riser design provides for simplification in design criteria associated with the subsea controller and umbilical system.