In the current multilateral trade regime, members often negotiate under the shadow of WTO law. In this article, we develop an explanation of how the legal vulnerability of members’ domestic policies affects ongoing multilateral negotiations in the trade regime. First, we show that, contrary to conventional wisdom, increased enforcement does not necessarily make actors shy away from further cooperation. Legal vulnerability can ignite a positive dynamic of cooperation because it can increase the set of feasible agreements of WTO members. In a second stage, we set out how the nature of the issue at stake, i.e. whether it can be easily disaggregated into negotiable units, affects whether this positive dynamics of cooperation takes place. We illustrate the plausibility of the argument by way of four in-depth case studies of how potential (or actual) defendants and potential (or actual) complainants in WTO disputes responded to the incentives brought about by legal vulnerability and negotiated in the Doha round.