How do UC Waitlists Work?

When on a waitlist at a UC, how do they decide who is admitted? For instance, if you’re in L&S at UCLA, how do they figure out who to admit first? Are the applicants ranked and then accepted by top rank or is the admission random?

As UC forum champion, I have been folllowing the UC admissions for many years. This year is an exception but unless someone actually works in admissions, no one can say for sure how the waitlist works and how admission decisions are made. Just know if waitlisted, you are a qualified applicant but the school did not have enough spots available to admit you. L&S at all UC’s does not admit by major so I am sure there is some hierarchy within the waitlist where applicants are ranked. Also some schools do have a required waitlist essay or statement which is part of the admission process. Unless the UC’s give full disclosure, some of this process will remain a mystery.