“I live in a neighborhood where many backalley garages have ajoining driveway space. My neighbor has recently erected a barrier preventing us from driving across that portion of “her” driveway. It’s almost impossible to drive in 1 of 2 cars into the 2 car garage with this barrier. What can I do?”
It depends on who owns the driveway, and what the terms are. I’m going to take an educated guess that the driveway is some sort of mutual easement, in which case there’d be a document (probably recorded against each individual property) which describes it.
Look at the document, for starters. Hopefully, it’ll have a detailed legal description of the easement, and that may tell you that your neighbor has in fact blocked off something that belongs (in part) to you and your other neighbors.
If not–and if you can’t convince your neighbor that she’s being a jerk–it’s time to go talk to an attorney. You might be able to make some sort of argument based on prescriptive rights or perhaps a necessary right associated with the easement (that’s unlikely, to be honest), but any of those sorts of arguments are way too fact-specific for me to guess based on your description.