In UK law you're allowed to work a patent for the purposes of research. You're also allowed to work a patent for personal use, as long as it's not commercial (distributing FOSS is a commercial activity, fwiw, as it could compete with for sale products).

Not allowing research use would be entirely antithetical to the patent system itself.

[This post is my opinion, not legal advice, and is provided for entertainment purposes only.]

The way patents are enforced is the patent holder sues for damages. This obviously means there needs to be some damages, i.e. they claim they lost sales or something. If you aren't using the patent to make products or money, just to do research, this is a hard case to make. I wonder if it actually ever happens in academia.

Note that everything you "invent" that builds on the prior patent, including what you publish, is still blocked by that patent. And even if you ultimately remove the patented part, they can claim it was needed in the research process. So wantonly infringing on a patent in your research doesn't hurt the patent holder anyway.

The research exemption used to be quite broad especially for universities who would often use it as carte blanche, but was narrowed significantly by Madey v. Duke University.

Keep in mind that software patents are only enforceable in the US and Japan. Everywhere else in the world, you can do whatever you want (only copyright applies).

For businesses, it's still a big deal most of the time because you usually can't really neglect the US market, but for academia, there is no such issues.

> Keep in mind that software patents are only enforceable in the US and Japan.

That is sadly untrue. There is a lot of confusion on this front because "software patents" are a specialized term of art that essentially means 'a patent that describes a procedure with no reference to a machine'. There was a period of time in the US when such patents were enforceable, but more recent cases have mostly changed that (Basically Diamond v Diehr in 1981 to CLS v Alice in 2014).

But all this is moot, because patents that apply to the software-implemented functionality of machines are common even without "software patents". I've followed more patents on software cases in _germany_ than anywhere else.

You're absolutely right about businesses. The US alone would be enough of a problem, but it isn't even the US alone that is an issue here.

> a patent that describes a procedure with no reference to a machine

Essentially all software patents describe the von Neumann architecture and make sure to reference machines for this exact reason. Even when it runs on commodity PCs, the patent will still take a ridiculous amount of space to discuss how the RAM is attached to the CPU etc.

> To what extent were the SIFT patents enforced?

I don't know if the patent was ever enforce, but I know for a fact that some companies intentionally adopted SURF and variants derived from SURF due to the patent threat.