Kiefer Sutherland took happy hour to the extreme Tuesday ... boozing his face off at a downtown L.A. bar ... so much so he needed nearby pedestrians for support.
Kiefer -- who has been twice-convicted of DUI -- did not break the law. In fact, the bar manager at King Eddy Saloon says Kiefer himself realized he had too much J&B scotch and cut himself off.
K.S. wasn't driving ... he left that to his bodyguard. We contacted Kiefer's rep -- so far, no comment.