This was one of the first back issues of the JLA I ever bought, at "El Dorado", my first-ever comic book store. As you can see, it's Near Mint.
The Story: "Panic From a Blackmail Box!" by Gardner Fox, Mike Sekowsky, and George Roussos. The JLA get involved in a mysterious gang war between two super-powered gangs, the Bulleteers and the Pyrotekniks.
The gang's leader, Leo Locke, finds some helpful info buried in a box he found while fishing(!) and he uses it to trap the other gang. Since all this hugger-mugger takes place in Central City, it gets noticed by local police scientist Barry Allen...
Roll Call: Batman, Flash, Green Lantern, Atom, Hawkman
Notable Moments: A change of pace issue--the story is small in scope, a vast change from the universe-shattering adventures the JLA usually finds itself involved in.
This issue (and the next) were inked by George Roussos, not Sid Greene, and while Sekowsky's normally excellent storytelling and layout shows through(like this Hawkman panel, which I think has superb draftsmanship and an interesting angle), I think Roussos was not the best inker for "Big Mike."
Roussos' loose inking style wasn't enough to "reign" Sekowsky in a little, so you end up with panels like this, where even as a kid I wondered "Why does Green Lantern look so weird?"