Can my boss discipline me for using social networking sites during work time?

Yes, quite possibly. When you’re at work, you’re supposed to be working, so using online social networking on your employers’ time could be grounds for initiating a disciplinary process.

Your employer should have a policy on personal use of IT equipment, and should have made it clear to you what you are allowed to do, and what you can expect to be sanctioned for doing.

Your employer should also have a clear discipline procedure that must be followed properly, including your right to be accompanied into a formal meeting by a union representative or a co-worker.