Space activities rely on capital-intensive assets that benefit from deep technical expertise and from economies of scale. Because of these high barriers to entry, and because the practical operational space is ultimately limited, space actors enjoy an early mover advantage, allowing them to cement their leadership vis-a-vis others. The ensuing dynamic can create a secondary barrier of entry for prospective space operators: not only do they enjoy a more limited domain to operate in; they might also be deterred by prohibitive conditions that come with the use of necessary technology. Within market environments, this risk of displacement is typically met through competition and antitrust law. In the domain of outer space, likely due to the primacy of sovereign states as addressee of norms and the assumption of (commercial) space activities as inextricably linked with state action, there is no explicit equivalent. This text argues that the safeguards of the Outer Space Treaty and other sources of international space law contain implicit market power limitations and shows how these can be understood and applied through a treaty-native mechanism. We also suggest that the integrity of a functioning space services market is of immediate concern for emerging space nations. Ultimately, we argue that safeguarding against anti-competitive behavior is both within the spirit of international space law, required by it to a certain extent, and a critical element towards the realization of its underlying premise “access for all”.