Hate to break it too you budd, but most likely scenario is its his word against yours in a court room and most like he will win. I work for a local government agency just like the postal service and I carry pepper spray just for the dogs I encounter through the day.
I am directed that if Im the slightest intimidated by a canine to use the spray to avoid further bodily injury. And a judge would side with a local government municipality anyday as long as protocol was followed.
If you had proof that suggested he just walked on your property and sprayed your dog violently that wasn't so much as barking then maybe you'd have better odds winning this, but sadly that the way it goes.
Is it a dick move on behalf of the mail man, yes. Im with you a 100percent there. When I walk up to a door with barking dog I tell the tenant/home owner that it is in their best intrest to put the dog up. Usuallly if a dog bites a city official like me its put to sleep sadly.
Most of these situations can be avoided, but with the dog attack three days ago where a canine mauled a 17month old baby to death and heavily injuring the baby's grandmother, Dog cases are becoming a lose lose case for all dog owners.