Current jurisprudential trends empower the International Criminal Court (ICC) Prosecutor to override domestic investigative authorities in a manner that violates the letter and spirit of the Rome Statute. Sovereign states have primary responsibility to document, investigate and prevent atrocity crimes. Yet, current ICC practice subverts domestic enforcement efforts. No provision of the Rome Statute permits the Office of the Prosecutor (OTP) to substitute its unfettered judgment over the good-faith discretion of domestic prosecutors. ICC judges have created de facto institutional jurisdictional primacy by relying upon mere assertions regarding the insufficiency of domestic efforts. This trend is particularly problematic at the liminal phase from the preliminary examination (PE) to an authorised investigation because OTP policy preferences supersede good-faith domestic investigations and prosecutorial assessments. Juridical templates for assessing admissibility have been extrapolated from later phases of particularised cases into the PE phase. Current practice effectively eliminates sovereign prosecutorial discretion. Good-faith exercises of domestic prosecutorial discretion should not be constrained by post hoc Court-created straitjackets. This article dissects this problematic arc and proffers a model for harmonising domestic investigative efforts within the structure and intent of the Rome Statute. Its conclusions recommend reforms to ameliorate a foreseeable crisis of cooperation that could cripple an unreformed Court.