I have been asked by many interested parties, congressional staff and others, to explain my reasons for resigning from the 5-member President's Privacy and Civil Liberties Oversight Board (PCLOB). The best and most complete explanation is contained in two letters that I wrote on the date of my resignation last week -- one to my colleagues on the Board -- Carol Dinkins, the chair; Alan Raul, the vice-chair; and Theodore Olson and Francis Taylor, members; and the second to President Bush.

These letters are posted...