What about writing letters of recommendation, for either future employment or admission to an advanced degree program?

Again, it is required that you have written authorization from the student, if you are going to discuss anything about his orher performance, which is likely what the recipient of your letter will be looking for. In addition, if you are writing a letter of recommendation for admission to a graduate program, you may also be shown a copy of a form the student has signed waiving his or her right to view your letter. It is good practice to copy that form and retain it for your own records, along with the student's written authorization document.