Purpose -The purpose of this paper is to analyze the legal complications prevail towards the architecture of mutual policy design between trade and climate change regimes. The recent literature on this topic is mainly focused on commons and has significantly ignored the existing regulatory constraints between both the regimes. Therefore, in this study relevant WTO and environmental laws are critically examined in order to bring another side of literally work on trade-climate policy framework. Moreover, the time factor, role of developing countries and two approaches are also discussed that are important constituents to be considered during ongoing climate change multilateral talks. Design/methodology/approach -This paper has six parts in total. Part one comprises of "Introduction", part two gives "Overview of relevant WTO and climate change regulations", part three describes "Antithesis of WTO and climate change rules" and explains the differences that both regimes posses in the basics of their nature, part four enumerates that how to galvanize the anticipated disputes among both the regimes, part five is focused on the participation of developing countries and their possible reservations towards climate policy and, part six gives some concluding remarks. Findings -This study found four major points of caution while architecting climate change policy. First, the climate change policy gives excuse to certain economies to protect their domestic industry, which is supposedly the violation of WTO rules. Second, the disputes arise at WTO platform from the climate friendly trade policies would be a new inconvincible challenge. Third, the GATT article XX (general exceptions) and agreement on subsidies and countervailing measures (ASCM) are still not clearly defined under climate change regime. Fourth, the position of least developed countries (LDCs), there is no action plan as these countries are the most affected due to possible stringent trade-climate policies.Research limitations/implications -This research posses potential policy implication for both governments and international organizations, and provides new direction to trade and climate change researchers. It opens the way to critically examine the legal issues addressed in this paper which subsequently help both trade climate change regimes to overcome such regulatory differences with mutual consensus. Practical implications -As policy implication this study suggests that what has been achieved during last two decades over climate change issue, and how long would it take to achieve the reasonable targets? In-fact, the past work has succeeded to address the climate change as the global issue and it needs to be solved jointly but there is still a long way to make potential progress in order to architect the comprehensive policy and designing of multilateral agreements. It needs more time to constitute a climate change regime free from individual countries' political and economical interests and consensus amongst all major countries and group. Originality/value -...