What can I do about a crazy neighbour who lets her dog do its business on private property and driveways?

I have a neighbour who lets her dog go on people's private property. Yes, she picks it up, but that is not the point. It is not appropriate to do this. I have never seen anyone so bold and ignorant. No one else who has a dog does this. I have called by-law and they tell me they have no jurisdiction as long as she picks it up. Even the police told me to try and approach her first. I posted a note on her car about this behavioiur and it only got worse. I am a tenant living on the top floor of a duplex, and do not appreicate walking down the driveway over the residue from her dog's business. I do not know what else to do, and cannot afford a lawyer? Does anyone have any answers? Thanks.