This article analyses the manner in which the parliaments of the EU and the US – two key global strategic partners – participate in the shaping of transatlantic relations. The article argues that the European Parliament (EP) and Congress aim not only to influence their executive branches but also to act autonomously in the transnational arena through parliamentary diplomacy. They seek to secure concessions both formally by scrutinizing transatlantic international agreements, such as TTIP, as well as informally by exposing injustices and diplomatic misconduct through human rights advocacy and institutional pressure, such as in the cases of the NSA surveillance and CIA renditions. The article demonstrates that the EP and Congress have created capacities for internal scrutiny and transnational interparliamentary dialogue and that they utilize their consent powers to make claims, condition transatlantic negotiations and gain greater presence, visibility and influence in international affairs.