Sean advises clients, including early-stage startups, unicorns, and Fortune 100 multinationals on a wide array of domestic and international tax planning and tax controversy matters.

Sean has particular expertise advising clients on tax matters related to blockchain and cryptocurrency ecosystems. He has advised numerous clients on tax issues relating to token generation events, private token sales, NFTs, decentralized autonomous organizations (DAOs), and centralized and decentralized cryptocurrency structures. Sean’s clients in this space include protocol development teams, founders, investment platforms, cryptocurrency exchanges, and individual investors.

Sean also has experience representing clients in tax controversies. He has represented large multinational companies in advance pricing agreements, tax arbitrations, administrative proceedings against the IRS, in U.S. District Court, and in the U.S. Tax Court. Sean has also represented taxpayers in controversies relating to the taxation of cryptocurrency. His 2018 article in the Yale Journal on Regulation Bulletin was quoted by the dissenting opinion in the U.S. Supreme Court's 2024 ruling in Moore v. United States, a landmark case on the constitutionality of the Mandatory Repatriation Tax provisions of the Tax Cuts and Jobs Act of 2017.

Sean has advised several Fortune 100 companies on international and domestic tax planning matters, including transfer pricing, foreign tax credit utilization, GILTI, Subpart F, and international M&A and restructurings.

Sean is a lecturer in law at Stanford Law School, where he taught courses in Corporate Income Tax and Blockchain Tax. He has also spoken at events hosted by IFA and the American Bar Association on the taxation of cryptocurrency. During law school, Sean was a member of the Stanford Law Review, and was a student Bradley Fellow at the Stanford Constitutional Law Center. He clerked for the Honorable Dale S. Fischer on the U.S. District Court for the Central District of California.