The California State University system is a union shop. Most non-manager employees in the CSU system are covered by one of several collective bargaining agreements. When CSU wanted to make cuts in its overall employee compensation it only had one option under the agreements, that option was layoffs.
When CSU decided instead that it wanted to furlough university employees it had to go to the unions and negotiate a side agreement to do so. Employees who were in their unions then had an opportunity to vote to ratify that agreement and almost all the CSU unions voted to accept furloughs for one year.
At this time it appears the budget problems may go on beyond a year. You may see the unions and CSU negotiating again on this topic. Any tentative agreement that may come out of a future agreement would most likely have to again go through a ratification process.
Under the agreement currently in place, management is apparently being given a great deal of discretion in how they are dealing with furlough days. For example, at SJSU, President Whitmore has decided to not close the campus on at least some furlough days. Some university employees are being asked to work on some furlough days and to take other non-furlough days off instead.
This is not the understanding some employees had who voted for furloughs of how furloughs would be implemented. Many employees expected the campus to be closed on furlough days. These employees made other plans on these days (for example for daycare) and some resent that it is not being closed and resent the possibility that they could possibly be asked to work and to take other days off instead. These employees are sometimes feeling taken advantage of.
If employees do not feel that the university is respecting the spirit of the furlough agreement it may be a lot harder for CSU to get a second agreement ratified, if that becomes necessary. It is important for the universities to remember that university employees have made a sacrifice here and if that sacrifice is not respected, it may not ever be repeated.