This paper analyses Transatlantic Trade and Investment Partnership (TTIP) negotiations in order to assess how the move towards tighter economic integration within the EU–US strategic partnership impacts on legislative–executive relations in EU trade policy. The analysis examines the institutional, substantive and party political dimensions of national parliaments' scrutiny of the Common Commercial Policy. Based on insights into both domestic and EU channels of parliamentary monitoring of TTIP negotiations, the paper argues that, although the government remains the central object of democratic control, the involvement of national parliaments in transatlantic trade extends to encompass the EU's own transatlantic and trade policies. This is rooted in the legislatures' legal capacity to constrain the executive in the negotiation, conclusion and, where applicable, ratification phases of EU trade agreements. It is argued that national parliamentary influence takes the shape of politicisation of the legitimacy of the expected policy outcomes of these agreements.