In the mid-1990s, Garfinkel branched into the then novel field of arbitration and co-led Skadden's newly combined litigation and arbitration group for 12 years. Before long, the firm’s arbitration focus had spread to Europe and Asia.
As counsel, he enjoyed major arbitration victories in both commercial and treaty cases. He successfully represented Belgian-Brazilian brewer AB InBev in a US$2.4 billion UNCITRAL claim brought by Mexican competitor Grupo Modelo in relation to its merger with Anheuser-Busch; and secured a US$500 million ICSID award for the Mexican cement group Cemex (his client in more than 20 matters) for Venezuela’s expropriation of its assets under President Hugo Chavez.
He also sat as an arbitrator for the ICC International Court of Arbitration, LCIA and American Arbitration Association; served on the latter’s international arbitration committee and the Institute for Transnational Arbitration's advisory committee; and was president of the College of Commercial Arbitrators.
He was on the New York Chief Justice’s task force on commercial courts and for a time chaired the Second Circuit Judicial Conference. He was also trustee of the Historical Society of the New York Courts.