Current sustainability related approaches focus on corporate groups, but there is a slow and growing realization of a move from corporate governance to governance through contract. This move has a major impact on sustainability governance and the extent to which contracting can be used to outsource environmental contingencies, such as GHG emissions, in global supply chains. At the same time, the global regulation of transport sustainability seems politically improbable. As an alternate route to transport sustainability in global supply chains, I focus in this chapter on the role of lead firms in sustainability governance. My approach focuses on a trifecta of private governance, private law liability, and transnational regulation: individually each of the three approaches has its deficits, but together they complement one another in driving sustainability and may even help pave way for global regulation. Current state-of-the-art research is primarily focused on labour sustainability. I argue that similar approaches are spreading into transport contexts in relation to governing ‘Scope 3’ GHG emissions. Focusing on labour sustainability developments in private governance, private law liability, and transnational regulation should make it easier to improve on these also in relation to transport sustainability.