[femto]

I've never understood why some people say a license is needed for something on which patents have expired. What's the legal basis, or is it bluff?

I can understand that copyright exists in the documentation that describes AXI, but that copyright covers only their documentation and not your own implementation (or is some derivation claimed?). I can understand that trademark might exist in the name "AXI", so don't use that name. Trade secrets seem to be moot, if you're not associated with whoever is keeping the secret. If none of the above apply, what basis is there for demanding a license?

[shakna]

Licenses still apply post-expiry, in the US, Australia and a few other places.

It didn't use to be this way, but around the 80s the big precedents for this.

Most of the time, if you were a licensee before the expiry, then you continue to be so post-expiry. If however, you were not, then you have no existing contractual obligation, and can use it.

However it is something you need to consult a lawyer on, before making any decisions, because this area of law is more complicated than most, and is growing in complexity.

[femto]

Thanks. That makes sense, as a licensee signs a contract, so they will be governed by the terms of the contract, and the contract can presumably be written to outlast the patent. It suggests to me that when a patent expires then licensees are potentially disadvantaged compared to non-licensees. It highlights that one must make sure that licenses are written to terminate royalties on patent expiry, or think twice about licensing patents that are close to expiry.

[shakna]

Just to add:

Usually royalties do go down after expiry in contracts.

Contracts also usually cover a lot more: Support, documentation and other guarantees.

This means there's a few businesses out there, that even after patent expiry still choose to renew their license.