I think the “one new member per year” was a contrivance of the editors at DC Comics during the Silver Age to keep both the Justice League and the Legion from growing unwieldy.
Also allowed them to exclude Hawkgirl when Hawkman was selected by the JLA. The similar rule over at the Legion was “no two members with the same superpowers,” a rule ignored whenever the writers felt like it.
I think the “one new member per year” was a contrivance of the editors at DC Comics during the Silver Age to keep both the Justice League and the Legion from growing unwieldy.
Also allowed them to exclude Hawkgirl when Hawkman was selected by the JLA. The similar rule over at the Legion was “no two members with the same superpowers,” a rule ignored whenever the writers felt like it.