unless the master or your supplement agreement says otherwise, then local,state, federal laws usually prevail. If it is legal to smoke while driving, then you should be able to light up. We have the same arguments here about cell phones. They try to make us quit but it is legal in our state, so no discipline.
I am pretty sure that local, state and federal laws supersede contract language.
i am from Arizona - i don't smoke but I thought that Arizona instituted a new law of no smoking in vehicles. I know that a couple of states have laws that do not allow you to smoke in the car if children are present.
Because I don't smoke I did not pay close attention. Call the Arizona DPS or visit the website. It may have the info posted.
Also - You should find out through your District Safety department what the rules are. If your district has a rule of smoking in a vehicle while driving or on work time, you may find yourself in for a fight especially if there is documentation that you have been notified. I am assuming that the safety ride checklist would show what your supervisor put in the comments section.
Remember Arizona law will take precedent so check that out first.