Marik String is an American attorney, national security expert, and U.S. Navy officer, who served as Acting Legal Adviser of the U.S. Department of State from 2019 to 2021.

[2] He then worked as an attorney at Wilmer Cutler Pickering Hale and Dorr, where he specialized in economic sanctions and national security law.

[1] String was selected to serve as acting Legal Adviser of the Department of State in 2019, succeeding Jennifer Gillian Newstead.

[12] He serves as one of four U.S. members of the Permanent Court of Arbitration (The Hague) and the U.S. National Group, the nominating body for ICJ judges.

[13] During his tenure, String also appeared on various briefs before the U.S. Supreme Court, including in Federal Republic of Germany v. Philipp, which examined the scope of the expropriation exception of the Foreign Sovereign Immunities Act (FSIA),[14] Nestle USA, Inc. v. Doe, which examined the scope and application of the Alien Tort Statute (ATS),[15] Republic of Hungary v. Simon, which examined the application of the doctrines of international comity and forum non conveniens under the FSIA,[16] and Mutond v. Lewis, which involved the scope and determination of conduct-based immunity for foreign officials in civil litigation in the United States.