Is it legal for the federal government to specify a font license other than “This is released into the public domain”? They automatically give up all copyright upon publication, which ought to exhaust any licensing terms.
If a license is granted to a work and the US government accepts that license and then publishes derivatives of that work, the US government releases its derivatives into the public domain without regard for the original licensing, as they have complied with the terms of the license to them and have no legal right to encumber their fork with any restrictions. Licenses depend on copyright, without which they are unenforceable, and the government is prohibited from copyrighting any work. The license clause should, therefore, be invalid and unenforceable upon any derivatives of this work, regardless of the accidental inclusion of it.
My idea is being hashed out on their GitHub, though sadly I suspect they’ll need lawyers to advise them rather than HN commenters such as I: https://github.com/uswds/public-sans/issues/30
IANAL, I believe the whole idea behind GPL is to make sure GPL supersede what you might claim otherwise. So if the federal government can possibly make a derived work into public domain (or crown copyright if UK) instead of GPL, that's a loophole in GPL!
(I know this work is not GPL, but similar idea applies)
Public domain code ain't GPL-compatible though unless it's explicitly released under a "license" that functions as a public domain grant (e.g. CC0, 0-clause BSD, WTFPL, etc., though WTFPL has some legal wording issues IIRC), the reason for this being that not all jurisdictions recognize the concept of "public domain" and thus require explicit license terms.
I don't know any jurisdictions that don't recognize the concept of “public domain”, but there are some that define “public domain” differently than it is defined in the US.
In the US “public domain” means “without copyright”, while in some other countries it means “without authors rights” (authors rights are a superset of copyright). The problem here is that some authors rights (both in the US & in those countries) are “inalienable”, meaning they can't be given or taken away (although there might be exceptions listed in the law).
Public domain may be incorporated into a GPL project if it is relicensed at time of commit under GPL by a committer whose country honors public domain to the degree necessary, but it may not coexist in a dual-license scenario with GPL, and that commit’s relicensing has no implied effect on the public domain repository from which the content was drawn.
