I updated it to the JMT Conservancy since it seems more accurate, but there is no single authority. originally the trail was sighted north to south, starting in Sequoia. more traditionally it is hiked starting in Yosemite. four different organizations can issue permits for travel along the JMT, five if you include the portion that overlaps with the PCT. but no permits are JMT specific - they set entry trailheads, with few exceptions on which trails can be hiked or where you can camp.