One of the most respected heroes in the entire DC Universe is Nightwing, leading many comic fans to wonder: why he isn't on the Justice League? Dick Grayson was trained by Batman, led the Teen Titans, and is generally well-thought-of amongst his peers. If any hero in the DCU is worthy of inclusion into the League, then surely it would be Nightwing.
Throughout their shared history, Grayson is one of the very few people who has earned Batman’s trust. For instance, he was the first one Batman called after the Knightfall saga, tasking his former partner with taking up the Mantle of the Bat while he took more time to recoup. Some even argue that Nightwing makes a better Batman than Bruce ever did. It is entirely fitting that he would be Batman’s first and only choice to be the replacement team leader should anything happen to the team, and quite possibly was kept from getting a full JLA membership for that very reason.
In the “Obsidian Age” storyline that ran in JLA #68-75 in 2002, this is exactly what happened. Written by Joe Kelley and with art by Doug Mahnke and Yvel Guichet, the story finds the Justice League searching for a time-displaced Aquaman, only to then get lost in ancient times themselves. Before the team disappears, Batman activates his contingency. Using technology based on Mr. Terrific’s “T-Spheres,” several drones are sent across the world, gathering together a group of replacement heroes to form a new Justice League. Amongst their number are a collection of heroes both old and new: Green Arrow, Hawkgirl, The Demon, Firestorm... each one hand-picked to take the place of the World’s Greatest Superheroes. Each was chosen after a careful vetting process, but the only one Batman trusts to bring them together as a team is Nightwing, making him the Justice League's most underrated leader.
It makes sense from a strategic position. The Justice League may be composed of the most powerful beings in the DC Universe, but they’re not immortal. “They’re just people,” The Atom muses at one point during the “Obsidian Age” story, “Very special people... but sometimes, even very special people die.” Batman surely calculated the risks the members of the Justice League encounter on a daily basis, and realized not all of them would be coming back. Considering the Justice League just recently died in DC Comics, this is probably smart. Thus, Batman put a contingency plan in place should anything happen to any of them... which may ultimately explain why Nightwing isn’t a full-time member. After all, if the former Boy Wonder had been with the League when they attempted to retrieve Aquaman from the past, he would have been lost in time with the rest of the team. Ever the strategist, Batman knew that Grayson had to be kept out of the JLA roster in case just such an event ever transpired.
It’s a good thing, too, as the planet descends into chaos shortly after the Justice League goes missing. Nightwing and his ragtag group of heroes find themselves with their hands full, including having to deal with each other. Yet in spite of the personal conflicts that arise between the new team’s eclectic roster, Nightwing acquits himself well to the role of leader. The replacement League ably deals with the disasters left following the original team’s disappearance and eventually helps bring the classic team back into the present day. He may deserve to be on the roster, but it turns out that Batman was smart to keep Grayson out of the JLA Watchtower. Nightwing could never be a member of the Justice League full-time because they’ll need him should they ever fall again.