Three recently decided cases discuss the retroactive application of the Foreign Sovereign Immunities Act of 1976 to pre-1952 claims—Carl Marks & Co. v. Union of Soviet Socialist Republics, Jackson v. People’s Republic of China, and Slade v. United States of Mexico. These cases have conclusively established that the FSIA is not to be applied retroactively to pre-1952 events—i.e., to claims arising prior to the issuance of the Tate Letter. They do not resolve the issue of retroactive application of the FSIA to post-1952 events, however, and this issue is currently engulfed in confusion. This Comment attempts to resolve this confusion and propose a solution to the retroactivity problem. Section II delineates the retroactivity issue, while Section III discusses the history of sovereign immunity and describes the FSIA in detail. Section IV outlines the sources of confusion in the area of FSIA retroactivity and identifies four basic principles which may be applied to circumvent the confusion. Finally, Section V proposes a retroactivity solution arrived at through the application of these principles.