When the FI was reorganised after 1945 and again based in France the IS again became its leading committee and was dominated by the figures of Ernest Mandel (Germain) and Michel Raptis (Pablo). When the FI split into two public factions in 1953 the majority faction led by these two men was known as the ISFI and the minority was refered to as the International Committee of the Fourth International (ICFI).
When the two factions were reunited in 1963 the new leading committee became known as the United Secretariat of the Fourth International. However a diminished ICFI remained outside the fusion process led by Gerry Healy and Pierre Lambert. This in turn split in 1971 and Pierre Lambert led a grouping known as the Organising Committee for the Reorganisation of the Fourth International (OCRFI) until it fused with a grouping led by Nahuel Moreno. That group split pretty soon and Lambert's tendency has since been known as the ISFI and publishes the journal La Verite.
See also: List of Trotskyist internationals