Knowing that this will vary from state to state, or maybe even city to city, can you explain implied easements to me? Like, this path from this public street onto this public property has been open for 50 years and now there's a locked gate there, and "we never meant for that to be used as an entrance." Is there some degree to which 50 years of unfettered access sets a precedent - is that a common law entrance now?
That depends on what people were doing on that path for fifty years. My state (Idaho) has a pretty common rule for prescriptive easements. (That’s what we call an easement that you get by open use of a property—an implied easement is one you get when you subdivide a single parcel and don’t leave a public right-of-way running onto one of the new parcels.) You get a prescriptive easement if your use of the pathway is:
• open and notorious (you’re crossing the path in a way that people can see you do it, not skulking furtively about)
• continuous and uninterrupted (there wasn’t another closed gate there)
• adverse and under a claim of right (you had reason to believe that you were allowed to cross the path, and the owner didn’t expressly permit you to use the path)
• with the actual or imputed knowledge of the owner of the servient tenement (the guy who owns the path knew, or had reason to know, you were using it)
• for the statutory period of five years (self-explanatory).
Note that third one: if I’m just putting up a sign that says anyone can use the path, it’s not a prescriptive easement. It’s only a prescriptive easement if you don’t have the right to use it, but I’m not stopping you. In this case, a guy loses his prescriptive easement, in part, because the other guys put a lock on the gate, but gave him a key to open the gate.
Because they’re hard to prove, prescriptive easements usually don’t actually happen except in cases where there’s an old surveyor’s error and a road spills onto somebody else’s property.