Sub-supplier's sustainability management in multi-tier supply chains: A systematic literature review on the contingency variables, and a conceptual framework

Sub-suppliers may violate sustainability standards for a variety of motivations, and focal firms' neglecting sub-suppliers’ violation despite stakeholder pressures to establish compliance at sub-supplier level can bring several tangible intangible risks firms. Focal firms apply sub-supplier's management (SSM) approaches extend sub-suppliers. As sustainable supply chain is fundamentally context-dependent, set contingency variables are expected impact the effectiveness SSM approaches. Through an up-to-date, comprehensive review literature on multi-tier, (MT-SSCM), 37 influencing in multi-tier identified. These then clustered two stages based their similarity terms common themes/points more efficient analysis. Propositions formulated explain way variation impacts each approach, when approach effective with regard variables, motivations not complying requirements ignoring noncompliance firm. A conceptual framework built according results findings study. Detailed practical implications also presented provide managerial insights managers. Finally, possible future research directions, that linked identified gaps, discussed.