One of the best, goofiest JLA covers, ever. I saw Hembeck do a repro of this in one of his books long before I saw the actual comic, and it made me want it so bad.
The story: "The Case of the Forbidden Super-Powers!" by Gardner Fox, Mike Sekowsky, and Bernard Sachs. The villainous (and unfortunately-named) Headmaster Mind creates a device causes natural disasters whenever the JLA uses their powers.
He enlists the Top, Matter Master, and the Tattooed Man(who now has his own show on TLC, I think), and when Batman and Green Arrow--who of course have no super powers--try to defeat them, it inspires the rest of the JLA to do the same, just without using their powers.
The cover is inspired by the moment in the story when the U.N. issues an injunction against the JLA from using their powers, so the JLA does what any group of masked heroes would do--form a picket-line outside the building!
Roll Call: Superman, Batman, Wonder Woman, Aquaman, Flash, Green Lantern, Green Arrow, The Atom
Notable Moments: Martian Manhunter does not appear, or is even mentioned, at all in this story.
Again, Aquaman takes a fairly substantial role. Nice.