Are managers at Credit Suisse (or other investment banks) allowed to act as a reference for a former employee, or does a blanket policy prevent this?

It is correct that the managers at credit Suisse are mainly allowed to act as a reference to their former employee when there may be a need. The need to act as a reference is permitted, provided no conflict of interest may be experienced between the former employees and the managers of Credit Suisse. However, when there is a possibility of a conflict of interest, it would not be permitted based blanket policy even though it states that it covers a group of things instead of one issue.