Spintronics is an emerging platform for logic circuit design. Though many approaches have been proposed, and several have met with some success, a number of challenges remain. Here, we introduce a new style of magnetic logic-mLogic-enabled by a novel four-terminal device. An input current pulse to the device switches the magnetic state by spin transfer torque-driven domain wall motion, which programs the resistance state of a magnetic tunnel junction in an electrically-insulated but magnetically-coupled path. Despite the low switching ratios of the devices, limited by the tunnel magnetoresistance ratio, logic circuits independent of CMOS may be configured using current-based signaling. Micromagnetic analysis of device performance and the concepts of mLogic circuit design are introduced, with SPICE simulation of logic gates demonstrating correct logic operation at supplies below 100 mV.