I work for a union hospital and they lay off by seniority. What I have seen happen, however, is that they may add pressure to the senior employees to retire out or take a package, but now, with no money available, I don't believe that a package will be created in this case.
I have not seen this be a departmental issue. They will close the services that do not bring in enough revenue, but then, absorb those nurses into the main hospital, then, according to whatever numbers they gave to lay off, went by seniority. Another thing I have seen is the increase in grievances, because management will also use this opportunity to scrutinize time and attendance records, and increase the disciplinary actions. It is harder to fire union members, but if management is diligent enough, they can usually terminate a person within a year by doing the proper steps. Proper steps in my place of work is to review the attendance for patterns (ie, calling in before or after the weekend-especially if you are already off to try and bridge time together), calling off on paydays or day after, calling off on holidays or adding sick days to extend vacation are some prime examples.
They will begin with an informal meeting, then elevate to a write up, then, require documentation for each absence, to warning, suspension, recommendation for termination and finally, if the person does not quit, to meet downtown for the oath meeting, where the arbitrator makes the final decision (which is usually termination).
If they are able to get rid of people based on time and attendance, they may be able to preserve some of the better employees. If not, then, in the event of a layoff, it will be seniority. Also, unions are known to backfield people to their previous positions. For example, if a person received a promotion from head nurse to nursing supervisor and it is decided that they intend to lay off some supervisors, some can bump back to head nurse. Those that choose not to are then terminated. This cross bumping can become a hot mess, especially in a corporation like mine, where we have at least 8 other hospitals. Some have been bumped to places that are totally inconvienant to travel to, or to departments they have not chosen to. Their feeling is a nurse is a nurse and can be trained. Sucks, I know.