There are software patents in EPC countries (which includes EU, UK), but not software patents as such. A sibling noted that USA now requires a real-world effect, that change apparently mirrors the situation under EPC: software here can be patented if it makes a technical contribution, ie it must do something outside of the computer (or something that simulates something outside of a computer! see Halliburton).

What is and isn't technical is largely down to convention and can't be readily reasoned over IME. In the UK you only need to be familiar with about a half-dozen pieces of caselaw to be able to make a pretty good guess.

It's established caselaw that compression is a mathematical method (not patentable); but you can implement that as a computer program (probably not patentable); but you can apply that to image compression (probably patentable, see Vicom).

Any opinions here are my own and do not relate to my employment. This is not legal advice.

EU law only excludes patents for software “as such.” https://www.iam-media.com/regionindustry-guide/patents-in-eu.... You can still patent inventions embodied primarily in software so long as it’s in the context of an industrial or consumer application. So you can’t patent RSA, but you can patent a phone that uses RSA to securely transfer data.

Since the Supreme Court’s Alice decision in 2013, which tightened the longstanding exclusion to patentability for “abstract ideas,” it’s probably slightly harder to get (or keep) a software patent in the US than in the EU. Just because US courts are more willing to look past hardware aspects of an invention to see if the “gist” of the invention is an abstract idea implemented in software.

When hardware is designed to be controlled by software, then you can't exclude software from the patent, because such patent would describe nonworking hardware. But that software isn't patentable separate from hardware.

Here’s a thought experiment: take a look at the Tillitis Key: https://tillitis.se It’s a security dongle that can execute arbitrary programs. It’s hardware is actually a RISC-V core implemented on top of an FPGA, with some firmware on top to load the user programs.

Now the firmware is a kind of software, so patent should not apply, right? Heck one could even argue that the configuration of the FPGA should not count either, only the FPGA itself may count. There’s a problem though: the keys are locked.

They kinda have to be to deliver their security promises, and prevent the secret key in the device from leaking, either by accident or by adversarial extraction. But then what do I have? A hardened piece of… hardware actually. And all the patents that didn’t apply "because software", now do.

Or maybe they do not, I’m not a lawyer. I just wanted to highlight how fuzzy the frontier could be.

There are no software patents in the US either, as of 2014, except ones that have a physical effect on the world. Compression, encryption, and data structures are basically the only allowed software patents.