To terminate or not to?

Hi, I would like to ask if it's legal to terminate a regular employee for almost 12years for drinking liquor inside company premises? As per our company policy, it is for dismissal on the first offense. BUT my point is, this particular employee had been with the company for 12 straight years. I already gave the notice to explain and he admitted the offense. 2nd notice to complete the 2 notice rule for termination for just cause is the termination letter.

Can that employee file for illegal termination incase i terminate him? Or maybe moral dmagaes or somtehing?

Need advice. Please help. Thanks.

it depends on what his job is and if he was on duty. if office clerk, i'd say suspension. if driver, guard, operates machinery, termination is warranted.