I'm a member of a sporting club which rents a building which backs onto an alleyway that has an attached car park. Normally we park there at night, and have without incident for close to 10 years now. Recently a commercial tenant has moved in to one of the other premises in the area and started to leave notes threatening legal action from lawyers if we park there. Do the "Private parking" signs and "Parking for Business X only" signs carry any legal weight if the car parks themselves are seemingly unattached to any properties? I believe the Private Parking Act 1986 (SA) covers it: On the topic of penalties, what are the restrictions on having a car towed? Can a private citizen really have someone else's car towed without their knowledge?