“cOAlition S says that the RRS works through two mechanisms: prior license and prior obligation. If funders or employers want a prior license to an academic’s work, their legal teams will add terms to their funding or employment contracts to create that license. But when authors only have an obligation or desire for immediate open access, RRS language sounds like an empty assertion based on a fundamental misunderstanding of how licensing works.
A Creative Commons license is an agreement between Licensor and Licensee, not something applied by mere assertion. If I, as someone without a Plan S funder (for now), use RRS language and say, “I have applied a CC BY public copyright license to any AAM version arising from this submission”, this is sadly not a notice about an actual prior license. At best, all I have made is an offer to license. The recipient of my submission needs to agree to accept my paper under the terms of the CC BY license, as the license itself states, “By exercising Licensed Rights (defined below), You accept and agree to be bound by the terms and conditions of this Creative Commons Attribution 4.0 International Public License…”
There is no obligation for publishers to accept the license. For example, a recent acceptance letter from a Springer Nature journal explicitly rejects RRS language….”