Do I need to give reasons for my PAIA request?
For public bodies — no. You do not need to justify why you want the information. For private bodies, you must show that the information is required to exercise or protect a right.
What can a public body refuse to disclose?
Limited grounds: national security, cabinet deliberations, commercial confidentiality, personal privacy of third parties, litigation privilege, and information protected by other legislation (e.g., criminal investigation). A blanket refusal citing "confidentiality" without specifying the ground is unlawful.