Under what circumstances can an attorney withdraw from an appeal?

Under clearly established law, all criminal defendants have a right to an advocate in mandatory appeals. See Douglas v. California, 372 U.S. 353, 355-58, 83 S.Ct. 814, 9 L.Ed.2d 811 (1963). Appellate counsel has an ethical responsibility of constitutional dimension to argue zealously those issues that counsel finds not wholly frivolous. See Anders, 386 U.S. at 744, 87 S.Ct. 1396. When an attorney believes an appeal would violate his or her ethical duty to refrain from making frivolous arguments, Anders requires counsel to "advise the court and request permission to withdraw." Id. A request to withdraw, "must, however, be accompanied by a brief referring to anything in the record that might arguably support the appeal." Id. The attorney must send the brief to the defendant and the defendant must be informed of his or her right to file a supplemental brief. See id.