I think it depends entirely on the purpose of the CLA. Different licenses say different things. Some merely assert that the signer is contributing under the lic

I think it depends entirely on the purpose of the CLA. Different licenses say different things. Some merely assert that the signer is contributing under the license under which the project is distributed. (Although you may consider it obvious, I am not aware of any existing case law in the US that asserts that submitting a patch necessarily comes with a grant of license to the copyright. And I can guarantee that there isn't case law in every jurisdiction around the world.) Other CLA purposes that seem reasonable to me include a guarantee that IF the contributor has a patent on the submitted code then a license to use that patent is granted to all users of the software. Even if the CLA does contain text granting some organization which manages the code the right to re-distribute under some other license, I may well be comfortable with that. Sometimes projects choose to move to a new license (GPL v3 wouldn't exist without this). Sometimes a company chooses to offer commercial licenses in addition to free ones. My willingness to contribute under these conditions comes down to the degree to which I trust the organization (realizing that the organization may change, but that almost no human endeavor can be achieved without some level of trust). On the other hand, if YOU wish to refuse to sign CLAs, you are certainly welcome to do that. But do not be surprised if some organizations reject your offers to contribute patches.