You could put it under a "PostgreSQL OR Apache-2.0 at your option" dual-license, so all contributors give you their code under both licenses, instead of needing to re-license later. The Rust project does this (MIT OR Apache-2.0) to get the patents clause from Apache while retaining compatibility with MIT and GPL.

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cyphar 4 days ago | parent [-]

If you do this, you need to have a very explicit policy for contributors to say they are contributing under both licenses, though this is something you need to have anyway if you are licensing under Apache 2.0 (a contributor could theoretically claim retroactively that their contributions were all MIT licensed and that they never gave you or any of your users a patent grant). (Most Rust projects do this.)

For other patent-shield licenses such a combination also removes most of the protections of the patent shield (a patent troll user can use the software under MIT and then sue for patent infrigement). However, the Apache 2.0 patent shield is comparatively weak (when compared to GPLv3 and MPLv2) because it only revokes the patent license rather than the entire license and so it actually acts like a permissive license even after you initiate patent litigation. This makes the above problem even worse -- if you don't actually have any patents in the software then a patent troll can contribute code under MIT then sue all of your users without losing access to the software even under just Apache 2.0 (I don't know if this has ever happened but it seems like a possibility).

IMHO, most people should really should just use MPLv2 if they want GPLv2 compatibility and patent grants. MPLv2 even includes a "you accept that your contributions to this project are under MPLv2" clause, avoiding the first problem entirely. It would be nice if there were an Apache 3.0 that had a stronger patent shield but still remained a permissive license (MPLv2 is a weak file-based copyleft), but I'm more of a copyleft guy so whatever.

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thayne 4 days ago | parent | next [-]

> However, the Apache 2.0 patent shield is comparatively weak (when compared to GPLv3 and MPLv2) because it only revokes the patent license rather than the entire license and so it actually acts like a permissive license even after you initiate patent litigation.

Isn't the idea that you could then sue the suer for infringing your patent?

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cyphar 3 days ago | parent [-]

Sure, if you have a patent. If you don't and the patent shield is intended more as pre-emptive protection then MPLv2 or GPLv3 are better.

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thayne 3 days ago | parent [-]

In this case, they do have a patent.

	▲	cyphar 3 days ago \| parent [-]
		Sure, that is the point of the original point of the article after all. I was speaking about the problem in general (I suspect most Rust projects--if not most projects in general--with this setup do not have patents). It also requires actively persuing a patent case which may result in the patent being rendered invalid, while a termination clause for the whole license just requires a far more clear-cut copyright infringement claim (possibly achievable purely through the DMCA system, out of court). But I'm not a lawyer, maybe counter-suits are more common in such situations and so either approach is just as good in practice.

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typpilol 4 days ago | parent | prev [-]

I always use the easy license for this stuff: Unlicense lol

	▲	cyphar 3 days ago \| parent [-]
		Great, but Unlicense doesn't grant patent rights so you have the exact same problem as MIT (actually it's even worse because Unlicense explicitly states that it is only concerned with copyrights multiple times).