Who decides if a journal switches from closed to an open access model?

Question

I have seen several journals switch from closed to open access models in the past. Is that simply a decision of the editorial board? Do they themselves have to convince the publisher (let's assume it is a commercial publisher)? And if they have to convince the publisher, what arguments/proof would convince the publisher?

Comments

Much depends on how you define the switch and who has control on the various pieces which make up what one calls the journal. There are various elements involved, see also https://freedomdefined.org/Elements_of_journal_freedom The proponents of "diamond open access" have been the most active in defining what are the shackles a journal needs to avoid. Some suggestions come from http://oad.simmons.edu/oadwiki/Journal_declarations_of_independence

Answer 1

The decision belongs to the journal owner or publisher, not the editors. 

But editors have some leverage. They can get the ear of the publisher more easily than outside advocates can, and the publisher usually want to keep them happy. But this leverage rarely suffices.

Sometimes when editors try to persuade a publisher to flip a journal to OA, and fail, they resign en masse and launch a new OA journal in the same niche. This is called a declaration of independence. See the crowd-sourced list of them from the Open Access Directory.