Alito, who worked in the Justice Department's Office of Legal Counsel at the time, said income and honoraria limits did not preclude Rehnquist from writing books, and that apparently Rehnquist was doing the work on his own without the help of court staff or the use of its facilities.
Alito's 1986 memo, released to the public on Friday, came during a bitter fight over President Reagan's nomination of Rehnquist to be chief justice. It was an apparent attempt to head off criticism over the thousands of dollars that Rehnquist accepted from William Morrow Co.
"We are unaware of any ethical rule barring judges or justices from writing books about their experience on the bench," Alito said in a 1986 memo to John Bolton, an assistant attorney general at the time who is now the U.S. ambassador to the United Nations.
"Indeed," Alito wrote, "it would seem that some such writing would be affirmatively encouraged by Canon 4, that permits judges to engage in certain 'quasi-judicial' activities, including teaching and writing, 'to improve the law, the legal system and the administration of justice,' if in doing so 'he does not cast doubt on his ability to decide impartially any issue that may come before him.' "