Before we talk about this further, can I ask: are you a lawyer, or have you discussed these topics with a lawyer? I'm not a lawyer, but I have discussed these topics with (variously) corporate lawyers and an Apache board member, and the impression that I've gotten from all of them is that this space is very nuanced and that one must be cautious. The way that the law will reason about issues does not always match the way that engineers will think. For example, I was astonished that a court ruled in Oracle's favor in Oracle v. Google, in a case where Google largely just implemented a documented, public Oracle API.

The whole SCO Linux controvery also seemed like a major problem for Linux at the time: https://en.wikipedia.org/wiki/SCO/Linux_controversies - it seemed to have a chilling effect that turned a lot of companies off to open source. The court case seemed to take several years to litigate, just to establish that Novell and not the SCO Group owned the copyright to the code. Why did that take so long to establish? The submission governance and CLA were put in place by some companies specifically to mitigate the threat of such a risk applying to them later. As Wikipedia explains regarding the rationale of CLAs: https://en.wikipedia.org/wiki/Contributor_License_Agreement#...

"Contributor Licence Agreements (CLAs) can be used to enable vendors to easily pursue legal resolution in the case of copyright disputes, or to relicense products from which contributions have been received from third parties. The purpose of a CLA is to ensure that the guardian of a project's outputs has the necessary ownership or grants of rights over all contributions to allow them to distribute under the chosen licence."

Emphasis is: "easily pursue legal resolution in the case of copyright disputes" (e.g., SCO Linux)

A lot of your argument seems to boil down to that because some people don't think there is a risk, that no one is right to rationally recognize a risk. I can't really comment on Apple's motivations for not requiring a CLA in Swift, just like I can't really comment on Apple's motivations for masterminding a criminal conspiracy to fix the price of ebooks (for which they were recently fined $450m). I can guess but I don't know for sure.

I think reasonable people could disagree about the risks involved in CLAs. It's not always the case that lawyers agree. As I pointed out originally, we don't have case law for all of this space. Insofar as you're implying that open source projects have been run without legal problems, I think you're wrong. Things like the SCO Linux controversy and the Oracle v. Google lawsuit about Java APIs make me feel like the industry as a whole is on less stable ground than everyone seems to think. Given that there are real cases where such problems have been specific issues, and given that many qualified people (not just me) explain this as their rationale, I don't think it's unjustified FUD. Can you provide a court case where one company sued another about an open source contribution, and the court clearly and convincingly ruled (in a short period of time): "You chose to contribute to open source, so live with it and stop wasting everyone's time". I haven't seen that. I've seen rather the opposite. The court will only muddle through what's happened with years of litigation at exorbitant cost. I've provided some examples of where this actually happened and has been messy, so if you wish to assert that this is all simple and CLA's aren't beneficial, then I'd like to ask you to provide a citation of a court case where such an issue was trivially resolved.

See also Jacobsen v. Katzer for case history. "The case is noted for its contentiousness, the parties filing 405 motions and other pleadings with the trial court, and two appeals to the Ninth Circuit Court of Appeals." (Wikipedia) The case was only resolved in 2010, and since it was settled out of court, I'm not clear whether it establishes binding precedent. As I understand it, the summary judgment left it open whether damages were owed. This is another example where litigation took years.

Are you also aware that the FSF employs copyright assignment to ensure that they can enforce licenses? https://www.fsf.org/bulletin/2014/spring/copyright-assignmen...

> In order to make sure that all of our copyrights can meet the recordkeeping and other requirements of registration, and in order to be able to enforce the GPL most effectively, FSF requires that each author of code incorporated in FSF projects provide a copyright assignment, and, where appropriate, a disclaimer of any work-for-hire ownership claims by the programmer's employer

CLAs are all about copyright assignment.

So in conclusion, I don't find your arguments convincing, in part because you seem to be overlooking or glossing over case history. From my perspective, there is a long and storied history of people actually running into problems in this area, and companies engaging in malicious lawsuits that are without merit specifically to harm competitors, and so on. There are examples of well-informed companies like the FSF taking steps specifically to mitigate these risks. For these reasons I understand why a company would want to protect itself from apparent and legally-advised risks with a CLA, and in general rely on more explicit contractual relationships rather than an open license agreed to without a clear meeting of minds.