SummaryNowadays, an important role in the world is played by Multinational Corporations (MNCs). They hire, produce, and influence the international economy, but also, they exploit, pollute. Their business activities might have a worldwide effect on human lives. The question of the responsibility of MNCs has drawn the attention of many scholars, mainly from the study field labelled “Business and Human Rights”. The present paper does not examine the topic under the same approach. The authors aim at presenting the issue in a broader perspective, exploring the concept of due diligence both in international and corporate law. In this paper, authors strategically use the uniformity of national legislations as a possible and alternative solution to the issue. They are aware of three fundamental factors: 1) the definition of MNCs needs to be as clear as possible, so to avoid any degree of uncertainty; 2) the outsourcing phenomenon interacts with that definition; 3) in case of no possibility to include outsourcing in the definition of MNC, the original question arises in a significant way.