Most parents want their teenager to grow up and become a productive happy citizen.  You want them to do well in the world and not allow others to take advantage of them. 

Unfortunately, when they try to assert themselves, we tell them they are back talking and now they are in trouble.  It is important that teenagers learn how to state their opinion in a respectful appropriate manner. 

One way is to role model for them.  This means talking to them as if they were your co-workers.  If you want them to respect you, you need to respect them.  This is not to say that you need to allow them to talk inappropriately, or allow them to violate rules you have set.