PJM Interconnection, the biggest grid operator in the U.S., has finally settled on a plan to prevent data centers from causing other customers’ utility bills to soar further in its 13-state territory. That plan relies heavily on states themselves, and the utilities they regulate, to force data centers to secure their own power supplies — or face the possibility of getting their power cut off during grid emergencies. But states, not PJM, are in charge of deciding which customers can connect to the grids operated by state-regulated utilities. Data center industry groups and other stakeholders warned that the plan could face legal challenges. That registry will be used to determine how much new large load exists in each of PJM’s zones, which in turn determines how much capacity each zone requires.