The Justice Society of America are an actual superhero team in DC comics. I believe they pre-date the appearance of the Justice League.
Holy cr@p I totally forgot about the JSA. JLA is old, but, yeah, pretty sure that JSA is older (and made less comics?) and they didn't have their own cartoon, like JLA, afaik : ). I seem to remember the JSA team being, not darker, but, hummm.. err.. hmm.. a tiny bit (less polished..?) grittier/tiny bit more Marvelish (who I usually preferred a little).
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I shoulda looked up the wiki, first. JSA has more less-known characters in it. Maybe that's partly where I get the less DC mainstream/less polished memory from.