Imagine the Wright brothers, after they invented their airplane, filed for a patent claiming “a machine for flying.” Essentially claiming a machine for what it does rather than how it does it. This is known as “functional claiming.”
Under previous Federal Circuit precedent, there was a very strong presumption that would give the Wright brothers the rights to any “machine for flying,” including things like the rocket or the Space Shuttle. But the Wright brothers only invented one type of machine for flying: why would they get to own things they didn’t invent?
The U.S. Supreme Court, in the early 20th century, saw the danger of these types of “functionally” defined inventions. As it explained in the seminal 1946 case Halliburton v. Walker:
In this age of technological development there may be many other devices beyond our present information or indeed our imagination which will perform that function and yet fit these claims. And unless frightened from the course of experimentation by broad functional claims like these, inventive genius may evolve many more devices to accomplish the same purpose.
In 1952, in what many commentators believe to be a response to Halliburton, Congress revised the Patent Act to allow functional claiming
Face palm. Why am I not surprised.
but did so with an important caveat. That caveat allowed inventors to claim their inventions functionally, yet the scope of the patent rights would be limited to only what the inventor actually structurally described in the patent specification (or its equivalents). The Wright brothers could claim their “machine for flying,” limited to what they actually described and things that were essentially the same, but they couldn’t stop someone from building the Space Shuttle.
Oh good, at least it looked like they were thinking.