From a speech by Pascal Lamy on the Government Procurement Agreement:
The GPA is a paradigm example of a trade opening instrument that also recognizes the need for governance mechanisms — in this case, the procedural rules that Parties to the Agreement must follow to ensure fair and transparent contracting practices and the domestic review or bid challenge mechanisms that the Agreement requires all Parties to put in place. These rules and enforcement mechanisms are built around the WTO's fundamental principles of non-discrimination, transparency and procedural fairness.
Non-discrimination and transparency are pretty clearly WTO principles. But is "procedural fairness" a principle as well? There are elements of various WTO agreements that could be said to involve procedural fairness, but it's not clear to me whether they are in there for their own sake, and thus would constitute a stand-alone principle, or if they are included as a proxy for getting at other issues (such as discrimination).
