That utility and freedom can conflict is illustrated by the potential drug addict. If we
prevent someone from trying a powerfully addictive drug, e.g. heroin, we contribute
more to their utility (and likely the utility of others) than if we allow them to try it. But
this is no objection, because Mill does not say that utility and freedom never conflict.
First, some freedom is ruled out by the Harm Principle for this very reason. Second, Mill
recognises that even freedom protected by the Harm Principle can conflict with utility in
some situations. His answer to it is to once again point us towards the bigger picture: