San Francisco Has New Law

And this new law conflicts with state law. Tobacco can no longer be sold to anyone under the age of 21, which is contrary to state law that says a person can buy tobacco products at 18.


Do you think this law will stand, or be shot down.
 
Will this lead to young smokers quitting?
 
How is it possible that a city can create a law that conflicts with state law? 

 
Link 
 
Note that the new law doesn't seem to prohibit smoking under 21, only buying tobacco products (e-cigarettes included).