The AAAS has now put on-line a list of all its members since its founding, searchable by subject. The omissions in the "Law" category are just breathtaking--they include such giants of law and legal scholarship in the 20th-century as Karl Llewellyn, Leon Green, Jerome Frank, Milton Handler, William O. Douglas, W. Page Keeton, John Henry Wigmore, and William Prosser. (Antipathy towards legal realists seems to be playing a role here, though doesn't explain all the omissions.) This is probably a worse track record of misses than even the Nobel Prize in Literature's!
ADDENDUM: Larry Garvin (Ohio State) identifies some other surprising omissions: Robert Jackson, Louis Brandeis, Arthur Corbin, Allan Farnsworth, Thurman Arnold, Max Radin, Charles Warren.