There are probably fewer than 100 lawyers in America who argue regularly before the U.S. Supreme Court and the highest state courts of appeal. And of those, a scant handful argue against corporate interests. That is particularly true when banks are involved: Lawyers who practice at big firms that regularly represent (or hope to represent) financial institutions avoid cases that endanger those relationships, even when one bank is suing another. But the renowned former U.S. Solicitor General Paul Clement left behind those concerns in 2011 when he left King & Spalding and joined Bancroft, a tiny appellate startup. Last year, Clement took up the Supreme Court case of small merchants suing American Express for antitrust violations. (He lost.) Now he’s turned up to oppose banks in one of the biggest-dollar appeals in the courts. On Tuesday, as first reported by the New York Commercial Litigation Insider, Clement appeared as counsel of record in HSBC’s motion, as a mortgage-backed securities trustee, for the New York Appellate Division, First Department to reconsider its Dec. 19 ruling on the timeliness of MBS breach-of-contract claims or else let the case proceed to the state’s highest court.