This article assesses the content and reach of the due regard obligation under Article IX of the Outer Space Treaty (OST). It first investigates if its substance might be spelled out despite its flexible and context-dependent nature. It then focuses on the ‘reach’ of the obligation, by examining, on the one hand, its practical ‘playing field’ vis-à-vis other ‘competing’ rules and, on the other, its potential application beyond Article IX OST. It concludes that, while it is possible to partially substantiate the content of this obligation, its status under international law remains uncertain and its implementation would be further supported by the adoption of more precise operationalizing frameworks at the multilateral level.