For an administrator, the only item that would block your access to a report is if the report has been Submitted and not yet Approved or Kicked Back.
To preserve the chain of custody of the report, no user in the system is able to modify a report that has been Submitted so that the state of the case is preserved for review.
For non-admins, other items that could come into play would be if a case report was owned by another officer and the user did not have "Modify Others Cases" Permission or if the case report had been approved and the user did not have "Modify After Approval" Permission. These can both be accessed and checked from the User Access page of the user in the Setup .
