As the nature of his powers have changed over the years, Green Lantern has had plenty of weaknesses, but his greatest weakness has seemingly been completely forgotten by his comic book writers. And only after one villain managed to come up with an exploit that is actually based on how Green Lanterns use their powers.
The Green Lanterns use their power rings to fly, automatically translate alien languages, and, most famously, to create energy constructs of any form the user wills. While these abilities needed some sort of weakness to balance them out, the solutions were less than perfect. The original Green Lantern, Alan Scott's weakness to wood stemmed from his subconscious belief that his powers couldn’t affect the material. The later Lanterns’ weakness to the color yellow came from the Fear entity trapped within the Green Lantern Corps’ central power battery. And while each of these explanations provide a plausible reason for those classic weaknesses, they still feel somewhat random. But one iconic Justice League villain exploited the very nature of Green Lantern’s powers to expose a new weakness that actually makes total sense.
In JLA issues #16 and 17,written by Grant Morrison and penciled by Howard Porter and Arnie Jorgenson respectively, the villain Prometheus infiltrates the Watchtower and systematically takes down the Justice League. He has prepared files on each League member with unique strategies to defeat each one. For Green Lantern, he has a device called a “Neural Chaff” that can disrupt the electricity in his brain, making it hard for Green Lantern to concentrate. This makes it impossible for him to muster his willpower and devise constructs for his ring to create. Without being able to use his ring, Green Lantern is left powerless, at Prometheus’ mercy.
While it is implied that the effects of the Neural Chaff fade over time and the Flash's healing ability can remove the effects effects by accelerating Green Lantern’s natural healing processes, in the heat of battle it is a devastating attack. This weakness is also even more debilitating than the weakness against wood and the color yellow, as those only prevent Green Lantern from affecting certain objects with his powers, while the Neural Chaff prevents him from using his powers at all. In addition, this weakness seems more natural than the other two, as it is based directly on how Green Lantern’s powers work. But outside of these JLA issues, this vulnerability is almost never used against the Green Lanterns.
This problem persists even in currently running series like DC vs Vampires, where Batman’s secret weapon against a vampiric Green Lantern is yellow paint. And this is despite the fact that the weakness to yellow shouldn’t be in effect any more after Parallax was removed from the central battery. This should have been unnecessary, as if Prometheus could figure out how to create the Neural Chaff, Batman could likely construct the technology as well. By ignoring Green Lantern’s natural and devastating weakness revealed by Prometheus, stories are effectively forced to artificially weaken some of their most popular and powerful characters.