News to me. And news, I think, to many thousands of Southern hunters who've gone for whitetails with .223-cal. Mini-14's and CAR-15's for the last 30 years.
It's considered a medium powered cartridge, not a high powered one like say a .30-06 or 7.62 mm NATO.
What states can you use a 223 for deer?
Some state by state answers, it's not comprehensive.