Green Bay Packers superstar Za'Darius Smith admitted to cops he had smoked weed shortly before he was pulled over for speeding ... telling an officer, "We had smoked earlier."
It's all in police video obtained by TMZ Sports ... which shows Smith and Packers rookies Rashan Gary and Kingsley Keke getting stopped on Sept. 29 in Racine, Wisc.
Smith was busted for doing 81 mph in a 60 -- but when a cop asked him how much weed he had in his vehicle ... the superstar pass rusher straight-up admitted to smoking earlier in the day.