PATRICK E. HIGGINBOTHAM, Circuit Judge:

A Florida state prisoner petitioned for federal habeas relief, challenging the constitutionality of a Florida statute that altered the mens rea requirement for state drug offenses.1 The district court, finding a due process violation, granted relief. We conclude that the state court did not unreasonably apply clearly established federal law, as determined by the U.S. Supreme Court, and reverse.

I.

A. Legal Background

Florida's Comprehensive Drug Abuse Prevention and Control Act ("Act") provides that, except as otherwise authorized, "it is unlawful for any person to sell, manufacture, or deliver, or possess with intent to sell, manufacture, or deliver, a controlled substance" or "to be in actual or constructive possession of a controlled substance."2 Violations range from misdemeanor offenses to first-degree felonies.3

The statute does not specify a necessary mental state, an issue the Florida Supreme Court first addressed in Chicone v. State.4 Reviewing a conviction for cocaine possession, the court held that the State was required to prove that the defendant "knew of the illicit nature of the items in his possession."5 The court reaffirmed that holding six years later, making clear that the requisite mens rea includes both knowledge of the presence of the controlled substance as well as knowledge of its illicit nature.6

The Florida Legislature responded swiftly to the latter decision. On May 13, 2002, it enacted a statute, now codified at FLA. STAT. § 893.101, amending the Drug Abuse Prevention and Control Act. The amendment provides in full:

The Florida Supreme Court recently considered a facial challenge to the Act as amended, brought under the Due Process Clauses of the Florida and United States Constitutions,8 of which the district court in this case did not have the benefit. The Florida Supreme Court upheld the statute as constitutional and in the process provided its definitive interpretation,9 tracking the text of the statute:

In short, the amendment did not completely eliminate mens rea for Florida drug crimes: it converted one aspect of mens rea from an element of the crime into an affirmative defense.

B. Procedural Background

A Florida jury convicted petitioner Mackle Vincent Shelton of five counts, one of which was for delivery of crack cocaine. Shelton's trial, which took place in 2005, postdated the amendment to Florida's Drug Abuse Prevention and Control Act. Accordingly, the jury was not instructed that Shelton's knowledge of cocaine's illicit nature was an element of the offense.11 Rather, the jury was instructed as follows:

The jury convicted, and Shelton was sentenced to eighteen years in prison.

Shelton appealed his conviction and sentence. Florida's Fifth District Court of Appeal affirmed without elaboration.13 Shelton then pursued state post-conviction relief, which the trial court denied. Again, the court of appeal affirmed without comment.14 At each stage, Shelton made a due process argument akin to the one presented here. Shelton then turned to federal habeas corpus relief, filing the petition giving rise to this case on May 18, 2007.

Shelton sought federal habeas relief on nine grounds. The district court rejected eight,15 but was persuaded on one ground: that the Act as amended is facially unconstitutional under the Due Process Clause. The court first concluded that "no deference is due to the state court's decision,"16 leading it to review Shelton's constitutional argument de novo.17 It then held that the Act as amended is facially unconstitutional because (1) its penalties are too harsh, (2) violations lead to substantial social stigma, and (3) it reaches inherently innocent conduct.18 The court granted habeas relief on that basis, staying relief pending appeal.19 The State timely appealed.20

II.

A. AEDPA Deference Generally

As in so many federal habeas cases reviewing state convictions, setting the proper scope and standard of federal court review is critical.21 A federal court may not grant a petitioner habeas relief on a claim that was adjudicated on the merits by the state court unless the state court decision was (1) "contrary to, or involved an unreasonable application of, clearly established Federal law, as determined by the Supreme Court," or (2) "was based on an unreasonable determination of the facts in light of the evidence presented in the State court proceeding."22 The state court's factual findings are presumed correct unless the petitioner rebuts those findings with clear and convincing evidence.23 Because Shelton brings a facial challenge, the state court's factual findings are not in dispute and Section 2254(d)(2) is not implicated.

The Supreme Court has explained the requirements of Section 2254(d)(1) as follows:

That is, "an unreasonable application of federal law is different from an incorrect application of federal law,"25 the former "a substantially higher threshold."26 To obtain relief under § 2254(d), the petitioner "must show that the state court's ruling on the claim being presented in federal court was so lacking in justification that there was an error well understood and comprehended in existing law beyond any possibility for fairminded disagreement."27

B. Deference in Shelton's Case

When reviewing the district court's grant or denial of habeas relief, we review its conclusions on legal questions and mixed questions of law and fact de novo.28 In this case, that review begins with the district court's determination of its standard of review. Drawing on the Supreme Court's recent decision in Harrington v. Richter,29 the district court concluded that the Florida appellate court rulings in Shelton's case were not "adjudications on the merits" entitled to deference because they were one-word summary affirmances.

In Harrington, the Supreme Court held that "[w]hen a federal claim has been presented to a state court and the state court has denied relief, it may be presumed that the state court adjudicated the claim on the merits in the absence of any indication or state-law procedural principles to the contrary."30 Under Harrington's general rule, then, a state court's simple one-word affirmance is presumed to be an adjudication on the merits of the petitioner's claim.31 But the district court located what it considered to be a "state-law procedural principle to the contrary" in a 1983 Florida Supreme Court case.32 In that case, according to the district court, the Florida Supreme Court supplied a state-law procedural principle "that a per curiam affirmance has no precedential value and is not an adjudication on the merits."33

The district court is only half-right, and not on the half that counts for federal habeas purposes. The Florida Supreme Court never held that a "per curiam appellate court decision with no written opinion" is not an adjudication on the merits; all it did was hold that the decision holds no precedential value for future cases.34 Indeed, a Florida district court of appeal recently "reiterate[d] that a per curiam affirmance without opinion is not an indication that the case was not considered on the merits."35 That position is consonant with this Circuit's recent en banc decision in another Florida habeas case, which held that "an `adjudication on the merits' is best defined as any state court decision that does not rest solely on a state procedural bar" and that deference is presumed "unless the state court clearly states that its decision was based solely on a state procedural rule."36 Here, the state court on direct appeal did not apply a procedural bar, and we are therefore compelled to presume that the court rendered an "adjudication on the merits" entitled to AEDPA deference.37

That conclusion significantly circumscribes the scope of our review. Unless we find that the state court's decision was "contrary to, or involved an unreasonable application of, clearly established Federal law, as determined by the Supreme Court,"38 we must deny relief.

III.

In order for Shelton to prevail here, he must be able to point to Supreme Court precedent clearly establishing that the Due Process Clause forbids the partial elimination of mens rea as an element of crimes analogous to those in Florida's Drug Abuse Prevention and Control Act, beyond any possibility for fairminded disagreement. That is a tall order, and as it happens, an impossible one.

It bears noting at the outset that, while the Florida Supreme Court's decision upholding the Act under the Due Process Clause39 does not bind us, it illustrates that five Justices of the Florida Supreme Court agree that no U.S. Supreme Court precedent renders the Act as amended unconstitutional. Were we to grant relief for Shelton here, we would necessarily imply that those Justices unreasonably applied clearly established federal law, as determined by the U.S. Supreme Court. If nothing else, that improbable outcome illustrates the uphill battle Shelton faces.

As it turns out, a fine-grained parsing of Supreme Court precedents is unnecessary to resolve our constricted inquiry. One very general principle can be distilled from the Court's cases in this area: legislatures have "wide latitude ... to declare an offense and to exclude elements of knowledge and diligence from its definition,"40 but they still must "act within any applicable constitutional constraints"41 when defining the elements of a criminal offenses. The Court has not drawn lines around this principle sufficient to dictate a particular result of the Florida court here, especially considering that Florida's elimination of mens rea was only partial. The Supreme Court has acknowledged that its work in this area has only just begun, noting twice that no court "`has undertaken to delineate a precise line or set forth comprehensive criteria for distinguishing between crimes that require a mental element and crimes that do not.'"42 Absent a Supreme Court case directly on point or a case so closely analogous that fairminded jurists would agree that its rule must extend to the present scenario, the Court's acknowledgment of uncertainty in this key principle effectively answers the AEDPA inquiry in Florida's favor.

Today, we need not march through all Supreme Court cases to prove the negative that the Supreme Court has never addressed Shelton's issue head-on, much less addressed it in his favor. It suffices to note that only once, in Lambert v. California, has the Supreme Court held a criminal provision unconstitutional under the Due Process Clause for failing to require sufficient mens rea. Lambert was an as-applied challenge to a Los Angeles municipal ordinance requiring felons to register with the city.43 The Court held that because failing to register is "wholly passive," the defendant lacked any notice whatsoever of her wrongdoing, violating her due process rights.44 The actions criminalized by the Florida Act as amended are sufficiently distinguishable — requiring affirmative acts of selling, manufacturing, delivering, or possessing, in addition to knowledge of the presence of the substance, all with an affirmative defense of lack of knowledge available — that we cannot say the state courts were unreasonable not to import Lambert's reasoning into this very different context.

Other cases that Shelton and the district court relied on are not square due process holdings. Rather, those cases avoid the due process question, sometimes invoking the rule of lenity, by reading a mens rea requirement into otherwise silent or ambiguous statutes.45 As Florida's statute is explicit in its partial elimination of mens rea, those rulings are no aid in Shelton's struggle to overcome AEDPA deference. Constitutional avoidance is little help to someone in search of clearly established constitutional law.

It must be said, too, that at a similar level of generality, a number of the Court's cases cut Florida's way,46 many of which the Florida Supreme Court relied on in upholding the amendment.47 It is plain that the analysis of the district court, addressing the due process question de novo, conflicts with the analysis of the Florida Supreme Court, but the district court implicitly concedes that its own result was not commanded by Supreme Court precedent in the manner contemplated by AEDPA. Its error here was made at the beginning — failing to accord deference to the state court decision on the erroneous view that it was not an adjudication on the merits of Shelton's appeal. To be clear, this Court expresses no view on the underlying constitutional question, as we limit our analysis to AEDPA's narrow inquiry. That inquiry leads us to conclude that nothing in the U.S. Reports decides or implies resolution of the novel issue of the Florida Act's constitutionality, and we cannot find Florida's adjudication to be unreasonable under AEDPA.

IV.

The district court's grant of habeas relief is REVERSED.48