A software license you drop into your repository, like MIT or GPL. It forbids nothing — anyone may use, modify, sell, or embed your code. But the day it ends up inside a system that scores, ranks, watches, or decides about people, whoever runs that system owes the public one thing: a plain-language statement of the principle they are acting on.
Your open-source code already runs inside other people's systems — credit scoring, tenant screening, workplace surveillance — and under MIT you will never know. Neither will the people those systems judge. The usual answer is an "ethical license" that bans the uses you dislike. Bans make the software non-free, are nearly impossible to enforce, and appoint you the judge of everyone downstream.
These licenses never say no. Instead, deploying on people carries one cost: the operator must go on the record — not to you, to the public the system touches. Silence or a false statement voids the license, and running the system becomes copyright infringement, the one thing courts reliably enforce. Sunlight, with teeth.
You license your code under the Kantian, Virtue, or Utilitarian Public License — three variants of one condition, compared below. For everyone who uses it as a library, nothing changes: no obligations beyond keeping the license file.
Someone ships it inside a system pointed at people — scoring, watching, ranking, deciding about them. Even if your code is five dependencies deep.
From that moment they owe the public a statement of the principle they act on, in plain language, kept current as the system changes. No statement, or a false one — no license.
"We score incoming mail by spam probability and sort it out of the inbox, and we hold that every mail provider may do the same."
Quillpost Mail Co. — posted 2026-04-14 · standing
Survives all three tests. An honest deployment answers §3.5 in an afternoon — and the answers are now on the record, quotable by every sender it filters and every regulator who asks.
"We score employees by keystroke rate and screenshot sampling, and the score informs termination — and we hold that every employer may watch the same way."
Tallyfloor Workplace Analytics — internal draft · legal advises against publication
Convicts itself. The KPL forbids nothing here. It demands the three answers — and written truthfully, they read as an indictment the operator signs. Publish that; or publish a flattering version and lose the license under §5, every further run copyright infringement; or stop. No committee needed — the document does the judging.
after Kant's Groundwork
What rule are you acting on — and would you accept everyone in your position acting on the same rule? A rule that only works as long as others don't follow it fails the test.
after Aristotle's Nicomachean Ethics
What does running this system make of the people it touches — and of you who run it? You become what you repeatedly do; so does a company.
after Mill's Utilitarianism
What good does the system do, what harm does it concede, and why is the trade worth it — for the people it affects, not for you?
Strict or lesser: the strict form's condition can never be stripped out, which makes it incompatible with the GPL and AGPL. The lesser form steps back where it meets GPL code, so the combination stays legal to ship. If you don't know which you need, take the strict one.
These are free-software licenses but not open source by the official definition, deliberately — the condition reaches the whole deployed system and triggers at run time. And large companies will likely treat your code the way they treat the AGPL: not by lying, but by banning it from their dependency lists. If that bothers you, these licenses aren't for you. If it sounds like the point — welcome.
In depth: how the six texts are built, whether declaration-based licensing can work at all, four traditions still waiting for their license (Levinas, Kropotkin, Spinoza, ethics of care), and the neighbors — firstdonoharm.dev, the JSON License, ethicalsource.dev and others.