The theoretical status of differential object marking (DOM) has given rise to numerous debates. In this paper we examine data from a set of languages with DOM (Uzbek, Hindi-Urdu, Estonian, Finnish), showing that previous theories addressing the problem of object licensing in DOM languages are insufficient to account for the facts. The complex morpho-syntactic behavior of direct objects in these languages provides further support to an account according to which DOM does not simply signal the difference between syntactically licensed objects, which are marked, and unlicensed ones, which are unmarked. Rather, DOM signals an additional licensing operation beyond that of structural licensing in terms of (uninterpretable) Case (following Irimia 2020, 2021, 2022).