More on amicus briefs, and in particular "the virtue of brevity" and "the vice of duplication," from Mayer Brown's Federal Appellate Practice treatise (some paragraph breaks added):
Courts have heavy caseloads, and judges and law clerks are therefore busy. For that reason, they tend to appreciate short briefs — or, more precisely, briefs that say no more than necessary for the court to decide the case intelligently. They also tend to pay more attention to short briefs. As Justice Scalia put it in his book on effective advocacy: "The power of brevity is not to be underestimated. A recent study confirms what we all know from our own experience: people tend not to start reading what they cannot readily finish." Accordingly,
a brief that is verbose and repetitious will only be skimmed; a brief that is terse and to the point will likely be read with full attention. So a long and flabby brief, far from getting a judge to spend more time with your case, will probably have just the opposite effect.
That is particularly true of amicus briefs. In Justice Scalia's words, the "injunction of brevity has special force here, since not even the demands of duty drive judges to read amicus briefs that are bloated." That view is shared by the justices' law clerks. On the basis of interviews with former clerks, the author of a study on amicus briefs in the Supreme Court concluded that "[o]ne of the foremost attributes common to the ideal amicus brief is brevity."
At least as a general rule, the same principle applies to amicus briefs in the courts of appeals. For two main reasons, an effective merits-stage amicus brief rarely requires every one of the 7,000 words authorized by the rules, and the author should try hard to resist the notion that the brief should be as long as the rules permit. Judges are aware that appellate briefs are like gas, expanding in volume to fill their container. Even though the rules permit a 7,000-word container, judges recognize and resent gaseous briefs.
First, apart from tables and certificates, an amicus brief need only include a statement of interest and an argument; it need not include a statement of the case or a statement of facts.
That is what the rules say. As a matter of practice, however, an amicus brief not only need not include a statement of the case or of the facts, it ordinarily should not include either type of statement. An amicus should assume that judges and law clerks do not wish to read procedural or factual — or any other — information that has been set forth in the party's brief and that instead they wish to get to the main point of the amicus brief as quickly as possible. Unnecessary preliminaries create a risk that the reader will lose interest in the brief and will — at most — merely skim the brief rather than studying it carefully.
Of course, there may be cases in which the facts are critical and the amicus concludes that they have not been effectively presented in the party's brief. In that circumstance, the amicus should include a statement of the facts of the case, but only a short one focusing on the most salient facts that underpin the arguments that the amicus will be making. If you draft a statement of facts for an amicus brief, go back after you complete the argument section to see whether you can excise some facts as unnecessary to the court's appreciating your points. As in any brief, factual propositions should be supported by citations to the opinion under review and the record, so that the reader is left with no doubt as to their accuracy. The author of the brief must also be meticulous in ensuring that the citations actually support the proposition; if they do not, the amicus risks losing credibility with the court.
Second, as to the argument, while it may be understandable for a party to believe that it must err on the side of saying too much, so as not to omit anything that might conceivably persuade the court to rule in its favor, there is no reason for an amicus to adopt that approach. On the contrary, if an amicus feels that it must err in one direction, it should err on the side of saying too little.
An amicus brief typically has a single, discrete objective. If that objective can be achieved in relatively few pages, then, as the survey of law clerks concluded, "it is counterproductive to obfuscate the important information the amicus seeks to convey by submitting additional pages." It is also counterproductive to risk irking the judges who will decide the case by submitting additional pages — to say nothing of the risk that the judges will only skim the brief or not read it at all. According to Justice Scalia, the author of an amicus brief should "[m]ake the one or two points (preferably one) that [he or she] think[s] will contribute something important and new — and close."
Brevity, of course, is merely an ideal toward which the amicus should strive; it is not an inexorable requirement. In particular, "the goal of brevity should not override the more important goal of helpfulness." There will be cases in which the objective of the amicus cannot be achieved in a few pages — cases, for example, in which there is simply a very large volume of important information to be conveyed to the court. There will also be cases in which the main justification for the amicus filing is that the party's brief is inadequate. In that circumstance, an amicus may well require all of the words it is allowed — or at least nearly all.
Whatever its length, an amicus brief should not merely repeat what the party and other amici say in their briefs. The need to avoid "me too" briefs is one of the most common admonitions to authors of amicus briefs — and with good reason. If an amicus brief simply repeats what another brief says, the court will give it little weight. It may not even be read, once an even cursory scan reveals the duplication, as where the amicus brief tracks the organization and headings in the party's brief. The court may go so far as to deny leave to file, if leave to file the brief is required.
Moreover, apparent duplication may lull the judges (and their law clerks) into giving the amicus brief such short shrift that they miss some unique gem of distinction or insight concealed within the morass. Supreme Court law clerks have indicated, unsurprisingly, that duplication is "the fatal flaw of an amicus brief." If an amicus does not have anything different to say, it should either stay out of the case or consider filing a consolidated brief with one or more other amici.
Part of the art of drafting an amicus brief, therefore, is not only to have something distinctive to say but also to make it apparent that there is something distinctive about the brief. This can be done in a very brief Introduction that explains what the amicus brief contains or addresses what is not in the party's brief. In addition, section headings should not mimic those of the party's briefs. In sum, just as it is often said that not only must justice be done, justice must appear to be done, so too the amicus brief not only should be different from the party's brief but it also should appear to be different.