As users are added to PolicyTech, the administrator decides which sites each user should have access to. When you assign a writer, reviewer, approver, or assignee to a content item (document, questionnaire, or campaign) and that user is not assigned or and has not been given access to the site containing the item, PolicyTech lets the user open that content item anyway in order to complete the assigned task. However, the user can only open the content item from the task in My Tasks or from the link in the notification email. The content item cannot be found using Search or Browse, since the user cannot select that site.
Keep this in mind as you assign users from other sites. Be sure that you're not granting a user access to a content item that the user should not have access to.