This is from the Understanding between the Republic of Korea and the United States regarding procedures under articles 21 and 22 of the DSU in the DS488 case:
4. Following circulation of the report of the Article 21.5 panel, either party may request adoption of the Article 21.5 panel report at a meeting of the DSB within 60 days of circulation of the report. Each party to the dispute agrees not to appeal the report of the Article 21.5 panel pursuant to Article 16.4 of the DSU.
5. If the parties agree to arbitration procedures under Article 25 of the DSU to provide for review of the report of the Article 21.5 panel, they will amend this agreement on procedures accordingly.
This seems to indicate that the U.S. is willing to forgo appeals "into the void" and also suggests some degree of openness on the part of the U.S. towards Article 25 as an alternative appeal process.
