Women are already legally allowed to go topless where I live in Ontario, Canada. That law was passed about 18 years ago. Almost no one does it, though. In fact, it's so rare that 99% of people that live here probably don't even know it's legal for a women to be topless in public.
When the law was first passed back in the late 90's only gross chicks went topless anyway. It was fairly disappointing.