A former Sullivan & Cromwell partner has resigned from the bar for billing his clients and firm more than $500,000 in fraudulent travel and entertainment expenses.

Carlos J. Spinelli-Noseda, a banking and finance specialist who joined Sullivan & Cromwell straight out of Harvard Law School in 1994 and became a partner in 2003, was facing a disciplinary investigation over a pattern of improper billing dating from roughly July 1998 to February 2008.

In a June 3 affidavit of resignation he submitted to the disciplinary committee of the First Department, Mr. Spinelli-Noseda admitted he could not successfully defend himself against charges of professional misconduct. Such resignations are frequently tendered when further proceedings are almost certain to lead to disbarment.

“I acknowledge that my actions violated the New York Lawyer’s Code of Professional Responsibility, notably DR 1-102(A)(4) inasmuch as my conduct constituted dishonesty, fraud, deceit and misrepresentation,” he stated in the affidavit, “and DR 1-102(A)(7) inasmuch as my conduct adversely reflects on my fitness and integrity as a lawyer.”

The Appellate Division, First Department, yesterday accepted Mr. Spinelli-Noseda’s resignation on the disciplinary committee’s motion In the Matter of Carlos J. Spinelli-Noseda, M-2908.

The decision appears on page 14 of the print edition of today’s Law Journal.

Mr. Spinelli-Noseda stepped down from his position at Sullivan & Cromwell in March. In a statement the firm said: “Upon discovery, the matter was promptly referred to the appropriate authorities. The Firm fully cooperated with those authorities, contacted affected clients and made restitution.”

Mr. Spinelli-Noseda’s lawyer, John B. Harris of Stillman, Friedman & Shechtman, said his client “deeply regrets” his conduct and had pledged to repay the firm.

“In cooperation with his former law firm, he has fully identified all of his improperly submitted expenses and is working to make all appropriate restitution,” said Mr. Harris.

Mr. Spinelli-Noseda, who is in his late 30s, is the latest large firm partner to engage in expense fraud.

Earlier this year, Samuel A. Fishman, a former Latham & Watkins partner pleaded guilty to criminal fraud charges after submitting around $300,000 in fake expenses. In 2006, former Wilmer Cutler Pickering Hale and Dorr intellectual property partner William P. DiSalvatore resigned from the bar in part over fake expenses totalling $109,000.

Stephen Gillers, a professor of legal ethics at New York University School of Law, said such cases appeared to be on the rise but said they remained “head-scratchers” to scholars in his field because the sums involved, even at six figures, were usually puny next to the partners’ compensation.

“We don’t understand why anyone would jeopardize their position and achievements for what amounts to pocket change for partners at large American firms,” he said.

Sullivan & Cromwell is one of the most profitable and prestigious corporate law firms in the country. Last year, the firm had profits per partner of $3.1 million, the third-highest in the nation, according to the AmLaw 100 survey by The American Lawyer magazine, a Law Journal affiliate. The firm also recently has been at the center of activity in the current turmoil on Wall Street, representing American International Group and Lehman Brothers, among others.

Mr. Gillers said the dominant theory among legal ethics scholars was that highly paid partners who engage in such fraud are expressing anger, possibly against firms they feel should pay them still more or clients whose vastly greater wealth generates resentment.

In his affidavit, Mr. Spinelli-Noseda said his misconduct typically involved characterizing personal travel and entertainment expenses as either client-related or business development.

Though based in New York, Mr. Spinelli-Noseda specialized in Latin American transactions and was regarded as one of the region’s top deal lawyers. He said in his affidavit that his conduct affected five clients. The firm would not identify them. Mr. Spinelli-Noseda has previously represented a variety of U.S. and Latin American financial institutions, as well as companies operating in the region.

Permitted by clients to fly first-class on international flights, Mr. Spinelli-Noseda said he sometimes flew economy or business-class, pocketing the difference from the first-class fare he would invoice.

To claim personal meals and lodging as business development expenses, Mr. Spinelli-Noseda said he would sometimes “list the names of business colleagues who were not actually present at these events and collect reimbursement from the Firm for expenses that the Firm would not have paid had it known the truth.”

In some cases, Mr. Spinelli-Noseda said, he submitted expenses for flights he did not take and meals he never ate.

According to the affidavit, one Sullivan & Cromwell associate participated in the expense fraud with Mr. Spinelli-Noseda. The ex-partner said he submitted fake expenses on behalf of an unidentified non-New York-based associate and then passed back to the associate a portion of the proceeds. Mr. Spinelli-Noseda said he understood this associate was no longer at the firm. A spokesman for Sullivan & Cromwell declined to comment on the associate described in the affidavit.

Mr. Spinelli-Noseda said he reported his misconduct to the firm on March 16 because he became concerned that his expenses might be audited. He reported himself to the disciplinary committee four days later.