Examining the early Israeli state’s claims to jurisdictional exclusivity in historical Palestine in the year 1948, this paper seeks to shed light on Israel’s inconsistent and, even, contradictory relationship with its predecessor, the British Mandatory administration in Palestine. Though May 15, 1948 marked both the formal end of the British Mandate for Palestine and the beginning of the state of Israel, sovereignty and jurisdiction did not spontaneously transfer over on this date. Rather, the Israeli assumption of jurisdiction was contingent upon its claims and abilities to do so. Looking at a series of early Israeli legal actions and court cases, this paper seeks to highlight that, in fact, Israeli claims to jurisdiction did not adhere to a unified line regarding the primacy of May 15. On the one hand, the Israeli state cast May 15, 1948 as the date on which it assumed jurisdiction. Intentionally positioning itself as the direct successor to British Mandatory Palestine, the Israeli state affirmed its recognition of British jurisdiction up until May 15. This claim to jurisdiction beginning on May 15, which was made in an explicitly political context and was part of broader attempts to assert itself vis-à-vis internal Israeli opposition as the sole legitimate sovereign in historic Palestine, was particularly evident in the Israeli state’s retroactive claim to jurisdiction in Jerusalem made in August 1948. On the other hand and, in a contradictory fashion, throughout this period, the Israeli judiciary and executive questioned their acceptance of British sovereignty up to May 15. Reexamining and reversing a number of British judicial decisions made prior to May 15, the Israeli state extended its legal reach back into the Mandate period, retroactively contesting British jurisdictional primacy. Combining these clashing Israeli claims to jurisdiction, this paper ultimately seeks to complicate the extant legal historical literature’s notion of May 15, 1948 as a self-evident transition and a clear point of separation, whereby the period of British Mandatory rule ended and that of the state of Israel began. In contrast, this paper seeks to portray the transition as a much messier process characteristic of the postcolonial predicament, in which the Israeli state, in a contradictory fashion, both relied upon and contested its colonial predecessor.