Many excellent comments, as usual. A number suggest that I am "soft" on plagiarism, especially when it is committed by professors and other "grown-up" writers, as distinct from students. I adhere to my heretical view that student plagiarism is a more serious offense. For one thing, the student who plagiarizes not only advances his career at the expense of his honest fellow students, but he doesn't learn a thing, whereas a professor who "steals" ideas or even phrases and incorporates them into his own work not only produces a better product to the benefit of his readership but may well improve his own skills. Itis one thing to copy blindly, another thing to use copied materials to create something new. Of course the author should acknowledge the copying; it is the failure to do so that is the wrong; my point is only that the plagiarizing work may have extra value by virtue of the plagiarism. Because faculty copying is more likely to be detected (the copy will be contained in a published work) and because exposure of a professor or other professional writer as a plagiarist is in itself a powerful shame sanction, and because as several comments point out computer search engines make detection of plagiarism ever easier, I continue to believe that the sanction of expulsion should probably be reserved for students. One commenter asked delicately whether Becker and I compose our blog "with external assistance." The answer is no, but the question underscores a particular concern that I expressed in my posting, and that is the fuzzy boundary of the concept of plagiarism. I do not think Becker and I would be guilty of plagiarism as currently understood if we used a research assistant to gather material for our blog. I am not even certain we would be thought guilty of plagiarism if we incorporated phrases or other material from a research memo prepared for us by a research assistant--I don't know enough about the conventions of blogging to have a view on this. (Clearly, however, if we lifted without acknowledgment material from another blog or some published work, we would be plagiarizing.) With novel media and novel expressive forms (such as the "managed book"), society needs new norms so that writers will know what they can and cannot do with or without acknowledgment. The conventions differ greatly across fields. I was reminded of this recently reading a very long law review article that contains a breathtaking array of citations to previous work. Nevertheless the author does not indicate which ideas in his article are original with him and which can be found in the literature that he cites. In fact many of his ideas are found in that literature. But I don't think he isguilty of plagiarism, because originality of ideas is not highly valued in law. Yet if he had copied actual passages (without acknowledgment) from a previous work, he would clearly have been guilty of plagiarism. Does this distinction make any sense? A little, I think, because one who copies ideas has at least to put them into his own words, and that requires some effort, whereas literal copying is effortless. But it is apparent that the meaning of plagiarism is highly field-bound and time-bound--that it is a culturally variable concept that requires careful mapping to avoid reckless accusations. One comment pointed out usefully that plagiarism can be a fraud on the public in a sense distinct from any I discussed--the comment gives the example of Margaret Truman, President Truman's daughter. A number of successful mystery novels were published under her name. Apparently none had been written by her--she had sold the use of her name to a pair of professional mystery writers. Finally, several commenters asked me how I use my law clerks, since I do write all my own opinions myself. I use the law clerks to study the cases before argument and give me their views as to how I should vote, what questions I should ask, etc.; to criticize my draft opinions and check them for accuracy; and, above all, to conduct research on the many factual and legal questions not adequately dealt with in the briefs of the parties or the other documents in the case. The contribution of the law clerks to my opinions is immense, though it does not include drafting; and likewise the contribution of my colleagues and, of course, of the lawyers and the lower-court judges. Consistent with the conventions of the judiciary, I do not acknowledge in my opinions the provenance of ideas contributed by colleagues, predecessors, law clerks, etc. Anyone seeking to evaluate a judge's creativity would do well to bear in mind the collective nature of the judicial product even when the judge does all his own writing.