I think this would make it tough to enforce the patent if it's actually commonly used. If I were somehow granted a patent on tap dancing, its common usage by others before me would probably cause my patent to be invalidated if I then tried to sue a tap dancer.
Not a patent lawyer, but IIRC, US patent law had some protections for things (including non-patented) that are already common practice.
EDIT: Clarity
Software patents get away with stupid shit like this all the time. Patent trolls claim they invented a software pattern and then sue everyone who uses it.
I think this would make it tough to enforce the patent if it's actually commonly used. If I were somehow granted a patent on tap dancing, its common usage by others before me would probably cause my patent to be invalidated if I then tried to sue a tap dancer.
Not a patent lawyer, but IIRC, US patent law had some protections for things (including non-patented) that are already common practice.
EDIT: Clarity
Software patents get away with stupid shit like this all the time. Patent trolls claim they invented a software pattern and then sue everyone who uses it.