U.S. Copyright Office, Guidelines for Registration of Fact-Based Compilations (Oct. 10, 1989).
These Guidelines advised Copyright Office examiners to register commercial telephone, street, and business directories, and parts catalogues and inventory lists that were not “clearly de minimis.” Examiners were advised to reject standard organization charts and any compilations containing fewer than four items. More difficult claims, such as mailing lists and subscriber lists, were to be rejected unless “the compilation represents a modicum of selection and/or arrangement authorship and the quantity of material compiled is not de minimis.
The Guidelines stated that telephone directories continued to be treated differently by all federal courts (i.e., even those that otherwise rejected sweat of the brow), and therefore should not be examined under "the usual Copyright Office criteria." Thus, in 1989 the Copyright Office moved almost entirely to an originality standard, rejecting sweat of the brow for all compilations except telephone books and similar directories.