Why Pho seems wrong: what "law" was violated?

The First Circuit's decision in Pho (basics here) asserts that a district court's decision to apply a 20:1 crack/powder ratio rather than the 100:1 ratio in the guidelines "was incorrect as a matter of law."  But as I read the opinion, I kept wondering what "law" was violated when the district judge decided, relying on the guidance of the sentencing commission, that this revised ratio would best effectuate Congress's commands in section 3553(a) of the Sentencing Reform Act.

Judge Seyla references 3553(a) throughout his opinion in Pho.  But, like Judge Breyer in the Booker remedy, all the references in Pho fail to mention the one plain textual command of 3553(a): "The court shall impose a sentence sufficient, but not greater than necessary, to comply with the purposes set forth in paragraph (2) of this subsection."  Notably, in footnote 3, Judge Selya quotes 3553(a) at length, but leaves out any reference to this explicit instruction from Congress to sentencing judges.  Also conspicuously absent in Pho's footnote 3 is the full text of 3553(a)(6), which commands judges to consider "the need to avoid unwarranted sentence disparities among defendants with similar records who have been found guilty of similar conduct." 

In light of the expert Commission work in this area — which finds that the guidelines' 100:1 ratio overstates the seriousness of crack offenses relative to powder cocaine offenses andcreates unwarranted sentence disparities between crack and powder sentencing — the application of a 20:1 ratio seems to be a more faithful application of Congressional directives in 3553(a) than is the opinion in Pho. (On this last point, consider the findings in Chapter 8 of the US Sentencing Commission's 2002 Report: "After carefully considering all of the information currently available — some 16 years after the 100-to-1 drug quantity ratio was enacted — the Commission firmly and unanimously believes that the current federal cocaine sentencing policy is unjustified and fails to meet the sentencing objectives set forth by Congress in both the Sentencing Reform Act and the 1986 Act.")

Put simply, the Pho opinion elevates the perceived intent of Congress over the plain text of 18 U.S.C. § 3553(a), which the Booker Court identified as the guide for district court sentencing decisions and for circuit court review of whether a sentence is reasonable.  (Where is a textualist like Justice Scalia when we need him?)  Moreover, the only clear intent of Congress — namely that, as exaplined by the Pho court, "Congress plainly believed that not all cocaine offenses are equal and that trafficking in crack involves different real conduct than trafficking in powder" — is fully served application of 20:1 ratio.  That ratio still, in one sense, treats crack offenses 20 times more seriously than powder cocaine offenses.  But apparently that's not good enough, so says the First Circuit.

Of course, in all this Pho criticism, I may be somewhat biased due to my work on an amicus brief that was soon to be filed in another First Circuit case raising the same crack/cocaine issue.  (It now looks like that effort might now be converted into a brief in support of a petition for rehearing en banc.)  But I find the opinion in Pho frustrating because it effectuates the most shallow conception of the goals of federal sentencing reform and falls prey to what Marc Miller has fittingly described as "Sentencing Equality Pathology".  After Blakely and Booker, I was hoping our common law of sentencing might do better, and today I am sorely disappointed.