Gary Hufbauer proposes the following:
Here’s one proposal, built on the force of “name and shame.” A visionary private foundation might convene a blue-ribbon bench of respected trade economists and lawyers, independent of any government or the WTO. The bench would be drawn from eminent persons around the world. It would be charged with grading new trade restrictions on an accelerated schedule.
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Panels would evaluate measures against the standards of the WTO, any relevant Free Trade Agreement (FTA), the G-20 pledge of November 2008, and any subsequent G-20 pledge. Reports would describe the measure and determine whether it violates the relevant standards. To repeat, the reports are meant to “name and shame”; they are not meant to be used as evidence in subsequent WTO disputes or other judicial proceedings.
I would suggest calling this group "Global Trade Watch," but that name has already been taken.