This is from the first USMCA Chapter 31 panel report, on Canada -Dairy TRQs, circulated today:
c) Purpose and Intent of the Treaty
As the Preamble to the Treaty explains, the Parties resolved to promote trade between the signatory states by creating “freer, fairer markets,” and “incentivizing the production and sourcing of goods and materials in the region.” In substance, the Treaty reflects an intent to open markets to a greater degree than was the case before its effective date and under predecessor agreements. In this dispute, Canada acknowledges that the “function” of the Processor Clause “has to be in accordance with the object and purpose of the treaty.” The Processor Clause unquestionably constrains Canada’s ability to deny access to non-processors, in furtherance of a more open trade relationship. The dispute is only the degree to which Canada is restricted. The trade liberalization background of the Treaty, while not definitive, serves to confirm the interpretation of the Processor Clause reached by consideration of the plain and ordinary meaning and the surrounding context.
(footnotes omitted)
The preamble to USMCA does say "freer," but it also says "fairer," and I think many people interpret "fair" in this context to mean trade-restrictive. Thus, the preamble points in two different directions on this issue.
And USMCA famously established more restrictive auto rules of origin, which was probably the biggest change from NAFTA.
Taking both of these factors into account, can we really say that USMCA "reflects an intent to open markets to a greater degree than was the case before its effective date and under predecessor agreements"?
(Not that I would say this point was crucial for deciding the interpretive issue at hand, and I think the same result would have been reached anyway, but I thought it was worth noting.)