I too found it hard to see any sensible justification for Judge Walton's footnote. Brief background:

Twelve current or former constitutional law professors — mostly conservatives, but also a libertarian (our own Randy Barnett) and two liberals (Vik Amar and Alan Dershowitz) filed an amicus brief arguing that (1) there are serious constitutional problems with special prosecutor Patrick Fitzgerald's appointment and (2) Scooter Libby thus has serious grounds for an appeal. This is relevant to the decision whether Libby should be let out on bail pending appeal, though the brief doesn't take a stand on this ultimate judgment, only on the inputs to that judgment (which is whether there's a close question about the appeal's merits). Four of the amici (Amar, Barnett, Dershowitz, and Judge Bork) also sign the brief as the lawyers.

Judge Walton allows the filing of the brief, but writes this odd footnote:

It is an impressive show of public service when twelve prominent and distinguished current and former law professors of well-respected schools are able to amass their collective wisdom in the course of only several days to provide their legal expertise to the Court on behalf of a criminal defendant. The Court trusts that this is a reflection of these eminent academics' willingness in the future to step to the plate and provide like assistance in cases involving any of the numerous litigants, both in the Court and throughout the courts of our nation, who lack the financial means to fully and properly articulate the merits of their legal positions even in instances where failure to do so could result in monetary penalties, incarceration, or worse. The Court will certainly not hesitate to call for such assistance from these luminaries, as necessary in the interests of justice and equity, whenever similar questions arise in the cases that come before it.

Yet this makes no sense. The point of amicus briefs is to express the signatories' views on some matter that they especially care about, in which they have a special interest or on which they have special expertise. A pro-abortion-rights organization, for instance, may file such a brief in an abortion rights case. Constitutional law professors who believe the Constitution, properly interpreted, supports abortion rights may do the same. No-one pretends that it's an "impressive show of public service," except insofar as any not terribly difficult action on behalf of a legal view that you think is the right view is a form of public service.

Such amici (whether advocacy groups or professors) surely incur no professional or moral obligation to start helping other litigants who raise other issues about which the amici don't are, or on which they lack expertise. Would you demand that a pro-abortion-rights professor who filed a pro-abortion-rights brief also file a brief in an assisted suicide case? Would you demand that he file such a brief even in an abortion rights case that raises a different issue? I would hope not — there's just no reason to think that because someone cared strongly about issue X he must now express his views about issue Y, or even that his views about issue Y would be helpful. The same applies here.

Now perhaps Judge Walton was suggesting that these amici would somehow have to file this brief only in cases that raise the same issue — the constitutionality of independent counsel. But while that's one way of interpreting his reference to "similar questions," it's not consistent with the rest of his footnote, in particular the preceding sentence: He's referring to "numerous litigants, both in the Court and throughout the courts of our nation, who lack the financial means to fully and properly articulate the merits of their legal positions" — but independent counsel prosecutions are not "numerous" (especially "throughout the courts of our nation"), and generally do not tend to involve litigants "who lack ... financial means to fully and properly articulate the merits of their legal positions." That's why I doubt that Judge Walton was only talking about the amici's supposed duty to file similar briefs only in independent counsel cases.

Yet even if he did mean this, what's the point of the sarcasm? I take it many of the signatories would be happy to express the same view in a future case raising the same issue. Some might not — and according to standard professional conventions, they are entitled to decide which litigants to speak on behalf — but many might. (Why would Amar or Dershowitz, to take the most obvious examples, treat a future Democratic special prosecutor target any worse than a future Republican?) The snideness thus seems at the very least premature.

Finally, as I understand it courts do have the power to require members of their bars (which may well not include many of the twelve amici) to represent some litigant, though that is a power that is rarely used today. But I doubt they have the power to require anyone to file a brief in his own name, a brief in which the person expresses his own view rather than just advocating on behalf of counsel — such a requirement would, I think, be a violation of the right to be free from speech compulsions.

And it seems to me that it would be unconstitutional for courts to require someone to shoulder an extra burden as punishment, retaliation, or other reaction to that person's past constitutionally protected actions, here the filing of a brief before the court. (The filing of briefs before courts is generally protected from retaliation by the Petition Clause, at least so long as the briefs comply with the proper court rules.) So if the court is threatening, or even sarcastically pretending to threaten, that he will "call for" assistance in a mandatory sense — rather than just suggesting he would offer a nonbinding invitation — then that strikes me as threatening to do something the court is not allowed to do.

Thanks to Leibowitz's Canticle for first pointing me to this.

UPDATE: Thanks to commenter Leo Marvin for pointing out an error in my original post; I wrote that the brief urged that Libby be let out on appeal — in fact, the brief declined to express a view on the subject, though the likely and probably intended (by many signatories) effect of the brief is to support the claim that Libby be let out on appeal.