OPINION
MOORE, Circuit Judge.Following a bench trial, Defendanh-Ap-pellant Daahir Caseer was convicted on May 15, 2002 of one count of conspiring to import cathinone and one count of aiding and abetting the importation of cathinone. The district court sentenced Caseer to two years’ probation. Caseer appeals his conviction, asserting that: (1) the controlled substances schedules in 21 U.S.C. § 812 and 21 C.F.R. § 1308.11(f) did not fairly warn him that possession of khat, a plant containing cathinone, was illegal; and (2) the district court committed clear error in finding that Caseer had the scienter required for conviction. We agree with the district court that Caseer’s conviction did not violate due process because the scien-ter requirement overcomes the threat to due process posed by the failure of the controlled substances schedules to identify khat as a source of cathinone. However, we REVERSE Caseer’s conviction and REMAND the case for further proceedings because, even viewing the evidence in the light most favorable to the prosecution, the evidence is insufficient to support a finding that, beyond a reasonable doubt, Caseer knew that khat was a controlled substance.
I. BACKGROUND
For centuries, persons in East African and Arabian Peninsular countries such as Somalia, Kenya, and Yemen have chewed or made tea from the stems of the native khat shrub (Catha edulis), which is known to have stimulant properties. Khat is often consumed in social settings, and many men in the East African/Arabian Peninsular region use khat. Joint Appendix (“J.A.”) at 164-65 (D. Ct. Op. at 5-6). Khat is legal in many parts of East Africa, the Middle East, and Europe; however, khat is illegal in the United States because it contains cathinone, a Schedule I controlled substance, and cathine, a Schedule IV controlled substance. See 21 C.F.R. § 1308.11(f) (listing cathinone as a Schedule I stimulant); 21 C.F.R. § 1308.14(e) (listing cathine as a Schedule IV stimulant). State and federal prosecutions relating to khat seem tó be a recent phenomenon, with the first reported cases appearing in the mid-1990s. See United States v. Sheikh, 367 F.3d 756 (8th Cir.2004); United States v. Hussein, 351 F.3d 9 (1st Cir.2003); Connecticut v. Gurreh, 60 Conn.App. 166, 758 A.2d 877 (2000); Warsame v. Maryland, 338 Md. 513, 659 A.2d 1271 (1995); Minnesota v. Ali, 613 *831N.W.2d 796 (Minn.Ct.App.2000); Ohio v. Samatar, 152 Ohio App.3d 311, 787 N.E.2d 691 (2003); Virginia v. Siad, No. CRIM 9463, 1997 WL 33421320 (Va. Cir. Ct. Mar. 6, 1997).
At the time of his trial in 2001, Daahir Caseer had lived in the United States for approximately three years, having spent the first sixteen years of his life in Somalia and seven years in Kenya. The events in question began in the spring of 2000, when Caseer approached John Eldridge, a bookkeeper at the Nashville, Tennessee taxicab company where Caseer worked, about the possibility of Eldridge traveling to Amsterdam, the Netherlands, to transport about fifty pieces of khat to the United States. Caseer explained to Eldridge that he could not make the trip himself because of visa issues.1 Caseer assured Eldridge that khat was an agricultural product and, at worst, customs might confiscate the khat and assess a fine.2 At trial, Eldridge testified that taxicab drivers in Nashville (80% to 90% of whom he believed to be of Somali or East African descent) frequently chewed khat and that, from his observations, khat was no stronger than caffeine. J.A. at 161 (D. Ct. Op. at 2).
Eldridge agreed to go to Amsterdam along with his girlfriend, Shannon Adams. Eldridge would receive $200.00 to compensate him for a day of missed work, and Eldridge and Adams’s travel expenses would be covered by Caseer and several other taxicab drivers who would be dividing the khat. Caseer also admitted during trial that three weeks before Eldridge’s trip, $1,500.00 had been sent to Amsterdam via Western Union. However, Ca-seer explained that the money wired to Amsterdam was unrelated to the khat and was bound for Somalia and that the khat was a gift from a Mr. Awale and three or four other people.
After arriving in Amsterdam on June 3, 2000, Eldridge and Adams met with Awale, who removed the contents of their luggage and left with the empty bags. The morning that Eldridge and Adams were to fly back to the United States, Awale returned with the three bags, now containing approximately 285 bundles of khat, or roughly 14,250 stems.
Eldridge and Adams returned to the United States on June 5, 2000, landing at the airport in Detroit, Michigan. A drug-detection dog at the Detroit airport alerted on one of the bags filled with khat, and a Drug Enforcement Agency (“DEA”) agent approached Eldridge and Adams. The pair agreed to cooperate with the investigation, and Eldridge placed a recorded telephone call to Caseer informing him that he had arrived and had cleared customs. At trial, Eldridge testified that during the telephone call, he complained about the amount of khat being greater than Caseer had indicated and reiterated his understanding that Caseer would pay his travel and related expenses. Caseer told Eldridge to trust him and that Eldridge did not need to discuss the matter with anyone else. Eldridge also testified that he met with Caseer after returning to Nashville and that Caseer told him they had not done anything illegal and would not be prosecuted, that he would take care *832of it, and that Eldridge should just stay quiet and not say anything about Caseer’s involvement.
Agent Panning then traveled to Nashville ’ and arrested Caseer. During questioning, Caseer admitted knowing Eldridge, Adams, and Awale. Caseer initially stated that Eldridge had purchased the airplane tickets; however, Caseer later said that a Hussein Abu-gar had made the purchase. At trial, Caseer stated that he may have lied to Agent Panning, but that he only did so because he was shaky and scared.
A sample of the khat seized by the DEA was sent to the Michigan State Police for analysis. Jurgen Switalski, a chemist employed by the Michigan State Police, tested the khat and concluded that it contained cathinone and eathine, but did not determine in what amounts. Switalski testified that, once khat has been harvested, the cathinone begins to dissipate and the eathine level rises; however, Switalski stated that he did not know how long it would take for the cathinone to degrade.
Eldridge, Adams, and Caseer were indicted on two counts: (1) conspiracy to import cathinone; and (2) importation of cathinone, and aiding and abetting the importation of cathinone.3 Eldridge agreed to testify against Caseer and pleaded guilty to misdemeanor possession of cathi-none pursuant to a plea agreement recommending six months’ probation. Caseer waived his right to trial by jury and was tried before a district judge for the Eastern District of Michigan.
At the conclusion of the prosecution’s case-in-chief, Caseer filed a motion for judgment of acquittal pursuant to Federal Rule of Criminal Procedure 29, claiming: (1) that his constitutional right to due process had been violated because he had not been fairly warned of the criminality of his actions; . (2) that khat qualified as a food item not subject to regulation by the Controlled Substances Act; and (3) that the evidence presented at trial was insufficient to prove beyond a reasonable doubt that Caseer intended to import cathinone. The district court took Caseer’s motion under advisement, later' denying the motion and finding Caseer guilty on both counts. The district court sentenced Caseer to two years’ probation. Caseer now appeals his conviction, asserting the fair warning and insufficiency-of-the-evidence claims first raised in- his motion for judgment of acquittal.
II. ANALYSIS
A. Fair Warning
Caseer first appeals his conviction on the basis that, because the schedule of *833controlled substances in 21 C.F.R. § 1308.11(f) lists cathinone as a controlled substance without making explicit reference to “khat,” he was not fairly warned that importing khat into the United States was illegal and thus his conviction violates due process. Whether a criminal statute is unconstitutionally vague is a legal question which we review de novo. United States v. Namey, 364 F.3d 843, 844 (6th Cir.2004) (citing United States v. Hill, 167 F.3d 1055, 1063 (6th Cir.), cert. denied, 528 U.S. 872, 120 S.Ct. 175, 145 L.Ed.2d 148 (1999)).
1. Establishment of Cathinone as a Controlled Substance
Section 812 of the Controlled Substances Act, 21 U.S.C. § 812, sets forth five schedules of controlled substances which are revised annually by rules promulgated by the Administrator of the DEA and published in 21 C.F.R. § 1308.01 et seq. See 21 U.S.C. § 811 (providing in part that “(a) The Attorney General shall apply the provisions of this subchapter to the controlled substances listed in the schedules established by section 812 of this title and to any other drug or other substance added to such schedules under this subchapter,” and setting forth procedures for adding substances to and removing substances from the controlled substances schedules); 21 U.S.C. § 812(c) & n. 1 (“Schedules I, II, III, IV, and V shall, unless and until amended pursuant to section 811 of this title, consist of the following drugs or other substances .... Revised schedules are published in the Code of Federal Regulations, Part 1308 of Title 21, Food and Drugs.”). Cathinone was not listed in the original Controlled Substances Act schedules but was added by agency rule as a Schedule I controlled substance in 1993:
(f) Stimulants. Unless specifically excepted or unless listed in another schedule, any material, compound, mixture, or preparation which contains any quantity of the following substances having a stimulant effect on the central nervous system, including its salts, isomers, and salts of isomers:
* * *
(3) Cathinone.1235 « Some trade or other names: 2-amino-l-phenyl-l-propanone, alpha-aminopropiophenone, 2-aminopropiophenone, and nore-phedrone
21 C.F.R. § 1308.11(f); see Schedules of Controlled Substances: Placement of Cathinone and 2,5-Dimethoxy-4-ethy-lamphetamine Into Schedule I, 58 Fed.Reg. 4,316 (Jan. 14,1993).
Although 21 C.F.R. § 1308.11(f) makes clear that cathinone is a controlled substance, neither the U.S.Code nor the Code of Federal Regulations controlled substances schedules refers to the plant from which cathinone is derived, Catha edulis, commonly known as “khat.” In contrast, several other chemicals classified as controlled substances are listed in the schedules along with their botanical sources. See, e.g., 21 C.F.R. § 1308.11(d)(23) (listing “peyote” as a controlled hallucinogenic substance and explaining that this listing refers to “all parts of the plant presently classified botanically as Lophophora wil-liamsii Lemaire, whether growing or not, the seeds thereof, any extract from any part of such plant, and every compound, manufacture, salts, derivative, mixture, or preparation of such plant, its seeds or extracts”); 21 C.F.R. § 1308.11(d)(28) (stating that the term “tetrahydrocannabi-nols” means “tetrahydrocannabinols naturally contained in a plant of the genus Cannabis (cannabis plant), as well as synthetic equivalents of the substances contained in the cannabis plant or in the resinous extractives of such plant, and/or synthetic substances, derivatives, and their *834isomers with similar chemical structure and pharmacological activity to those substances contained in the plant”); 21 C.F.R. § 1308.12(b)(4) (listing in Schedule II “[c]oca leaves (9040) and any salt, compound, derivative or preparation of coca leaves (including cocaine (9041) and ecgo-nine (9180) and their salts, isomers, derivatives and salts of isomers and derivatives), and any shit, compound, derivative, or preparation thereof which is chemically equivalent or identical with any of these substances, except that the substances shall not include decoeainized' coca leaves or extraction of coca leaves, wh[i]eh extractions do not contain cocaine or ecgonine.”).
However, the Supplementary Information published in the Federal Register along with the text of the rule adding cathinone as a Schedule I substance does explain the connection between khat and cathinone. 58 Fed.Reg. at 4,317 (“Cathi-none is the major psychoactive component of the plant Catha edulis (khat). The young leaves of khat are chewed for a stimulant effect. Enactment of this rule results in the placement of any material which contains cathinone into Schedule I. When khat contains cathinone, khat is a Schedule I substance. During either the maturation or the decomposition of the plant material, cathinone is converted to cathine, a.Schedule IV substance. In a previously published final rule, the Administrator stated that khat will be subject to the same Schedule TV controls as cathine, (see 53 FR 17459, May 17, 1988).4 When khat does not contain cathinone, but does contain cathine) khat is a Schedule IV substance.”). ' The U.S. Sentencing Guidelines also provide for marijuana equivalency with respect to khat-related offenses, but do not reference the chemical “cathinone.” United States Sentencing Guidelines Manual § 2D1.1 (Commentary) (2003) (listing one gram of khat as equivalent to 0.01 grams of marijuana); Amendments to the Sentencing Guidelines for the United States Courts, 60 Fed.Reg. 25,074, 25,079-80 (May 10,1995).
2. Application of Fair-Warning Doctrine to Khat-Related Offenses
At the heart of the fair-warning doctrine is one of the central tenets of American legal jurisprudence, that “[ljiving under a rule of law entails various suppositions, one of which is that ‘(all persons) are entitled to be informed as to what the State commands or forbids.’ ” Papachristou v. City of Jacksonville, 405 U.S. 156, 162, 92 S.Ct. 839, 31 L.Ed.2d 110 (1972) (quoting Lanzetta v. New Jersey, 306 U.S. 451, 453, 59 S.Ct. 618, 83 L.Ed. 888 (1939)); see also Connally v. Gen. Constr. Co., 269 U.S. 385, 391, 46 S.Ct. 126, 70 L.Ed. 322 (1926) (“[A] statute which either forbids or requires the doing of an act in terms so vague that men of common intelligence must necessarily guess at its meaning and differ as to its application violates the first essential of due process of law.”); Columbia Natural Res., Inc. v. Tatum, 58 F.3d 1101, 1105 (6th Cir.1995), cert. denied, 516 U.S. 1158, 116 S.Ct. 1041, 134 L.Ed.2d 189 (1996) (“[Bjecause we assume that man is free to steer between lawful and unlawful *835conduct, we insist that laws give the person of ordinary intelligence a reasonable opportunity to know what is prohibited, so that he may act accordingly. Vague laws may trap the innocent by not providing fair warning.’ ”) (quoting Grayned v. City of Rockford, 408 U.S. 104, 108-09, 92 S.Ct. 2294, 33 L.Ed.2d 222 (1972)).
Vague laws are subject to particular scrutiny when criminal sanctions are threatened or constitutional rights are at risk. See Vill. of Hoffman Estates v. Flipside, Hoffman Estates, Inc., 455 U.S. 489, 498-99, 102 S.Ct. 1186, 71 L.Ed.2d 362 (1982) (“The degree of vagueness that the Constitution tolerates — as well as the relative importance of fair notice and fair enforcement — depends in part on the nature of the enactment. Thus, economic regulation is subject to a less strict vagueness test because its subject matter is often more narrow, and because businesses, which face economic demands to plan behavior carefully, can be expected to consult relevant legislation in advance of action .... The Court has also expressed greater tolerance of enactments with civil rather than criminal penalties because the consequences of imprecision are qualitatively less severe .... [Pjerhaps the most important factor affecting the clarity that the Constitution demands of a law is whether it threatens to inhibit the exercise of constitutionally protected rights. If, for example, the law interferes with the right of free speech or of association, a more stringent vagueness test should apply.”); Belle Maer Harbor v. Charter Township of Harrison, 170 F.3d 553, 559 (6th Cir.1999) (“[Ajlthough we do not require impossible clarity in standards governing conduct, the court must apply a relative strict standard of scrutiny here where criminal sanctions apply.”) (citing Kolender v. Lawson, 461 U.S. 352, 361, 103 S.Ct. 1855, 75 L.Ed.2d 903 (1983); Springfield Armory, Inc. v. City of Columbus, 29 F.3d 250, 252 (6th Cir.1994)). As the Supreme Court explained in United States v. Lanier, courts safeguard criminal defendants’ due process right to a fair warning in several fashions:
First, the vagueness doctrine bars enforcement of a statute which either forbids or requires the doing of an act in terms so vague that men of common intelligence must necessarily guess at its meaning and differ as to its application. Second, as a sort of junior version of the vagueness doctrine, the canon of strict construction of criminal statutes, or rule of lenity, ensures fair warning by so resolving ambiguity in a criminal statute as to apply it only to conduct clearly covered. Third, although clarity at the requisite level may be supplied by judicial gloss on an otherwise uncertain statute, due process bars courts from applying a novel construction of a criminal statute to conduct that neither the statute nor any prior judicial decision has fairly disclosed to be within its scope. In each of these guises, the touchstone is whether the statute, either standing alone or as construed, made it reasonably clear at the relevant time that the defendant’s conduct was criminal.
520 U.S. 259, 266-67, 117 S.Ct. 1219, 137 L.Ed.2d 432 (1997) (internal quotation marks and citations omitted).
Although the doctrine of fair warning emphasizes the importance of citizens understanding what conduct is and is not prohibited, courts also frequently invoke the maxim that ignorance of the law is no defense. See Lambert v. California, 355 U.S. 225, 228, 78 S.Ct. 240, 2 L.Ed.2d 228 (1957) (noting that the “[t]he rule that ‘ignorance of the law will not excuse’ is deep in our law ....”) (quoting ShevlinCarpenter Co. v. Minnesota, 218 U.S. 57, 68, 30 S.Ct. 663, 54 L.Ed. 930 (1910)); see also Nash v. United States, 229 U.S. 373, 377, 33 S.Ct. 780, 57 L.Ed. 1232 (1913) *836(“[T]he law is full of instances where a man’s fate depends on his estimating rightly, that is, as the jury subsequently estimates it, some matter of degree. If his judgment is wrong, not only may he incur a fine or a short imprisonment, as here; he may incur the penalty of death.”). As we have previously observed, “The requirement of fair notice is not applied mechanically or without regard for the common sense judgment that people do not review copies of every law passed.” Columbia Natural Res., 58 F.3d at 1105.
Thus, while “[vjagueness may invalidate a criminal statute if it either (1) fails ‘to provide the kind of notice that will enable ordinary people to understand what conduct it prohibits’ or (2) authorizes or encourages ‘arbitrary and discriminatory enforcement,’ ” United States v. Bowker, 372 F.3d 365, 380 (6th Cir.2004) (quoting City of Chicago v. Morales, 527 U.S. 41, 56, 119 S.Ct. 1849, 144 L.Ed.2d 67 (1999)), the Supreme Court • has also stated that “the more important aspect of vagueness doctrine ‘is not actual notice, but the other principal element of the doctrine — the requirement that a legislature establish minimal guidelines to govern law enforcement,’” Kolender, 461 U.S. at 358, 103 S.Ct. 1855 (quoting Smith v. Goguen, 415 U.S. 566, 574, 94 S.Ct. 1242, 39 L.Ed.2d 605 (1974)). See Columbia Natural Res., 58 F.3d at 1105 (“As a practical matter, the Supreme Court considers the latter concern the more important. This reflects the common sense understanding that the average citizen does not read, at his leisure, every federal, state, and local statute to which he is subject.”).
The case at bar differs from most fair-warning cases' in that the criminal provision at issue here is not ambiguous in the traditional sense. Neither party has challenged the fact that 21 C.F.R. § 1308.11(f)(3) on its face explicitly establishes cathinone as a Schedule I controlled substance. Rather, the asserted constitutional defect of this provision is that through the definition of prohibited conduct by the use of an obscure scientific term, i.e., “cathinone,” persons of ordinary intelligence, even after reading the statutory text, would be unaware that khat is a controlled substance. In other words, the controlled substances schedule’s vagueness derives not from the language’s imprecision but rather from the schedule essentially being written in a language foreign to persons of ordinary intelligence. When a statute is precise on its face yet latently vague, the danger of persons being caught unaware of the criminality of their conduct is high. Cf. Bouie v. City of Columbia, 378 U.S. 347, 352, 84 S.Ct. 1697, 12 L.Ed.2d 894 (1964) (“The thrust of the distinction ... is to produce a potentially greater deprivation of the right to fair notice in this sort of case, where the claim is that a statute precise on its face has been unforeseeably and retroactively expanded by judicial construction, than in the typical ‘void for vagueness’ situation. When a statute on its face is vague or overbroad, it at least gives a potential defendant some notice, by virtue of this very characteristic, that a question may arise as to its coverage, and that it may be held to cover his contemplated conduct. When a statute on its face is narrow and precise, however, it lulls the potential defendant into a false sense of security, giving him no reason even to suspect that conduct clearly outside the scope of the statute as written will be retroactively brought within it by an act of judicial construction. If the Fourteenth Amendment is violated when a person is required ‘to speculate as to the meaning of penal statutes,’ as in Lametta, or to ‘guess at (the statute’s) meaning and differ as to its application,’ as in Connally, the violation is that much greater when, because the uncertainty as to the statute’s *837meaning is itself not revealed until the court’s decision, a person is not even afforded an opportunity to engage in such speculation before committing the act in question.”).
We have previously noted that the “general rule that citizens are presumed to know the requirements of the law ... is not absolute, and may be abrogated when a law is ‘so technical or obscure that it threatens to ensnare individuals engaged in apparently innocent conduct,’ because to presume knowledge of such a law would violate a core due process principle, namely that citizens are entitled to fair warning that their conduct may be criminal.” United States v. Napier, 233 F.3d 394, 397-98 (6th Cir.2000).
The use of scientific or technical terminology or terms of art common in a regulated field does not automatically render a statute unconstitutionally vague. See Vill. of Hoffman Estates, 455 U.S. at 501 n. 18, 102 S.Ct. 1186 (citing dictionaries defining “roach” as the butt of a marijuana cigarette and explaining that, “The Court of Appeals criticized the ... fail[ure] to explain what a ‘roach clip’ is. This criticism is unfounded because that technical term has sufficiently clear meaning in the drug paraphernalia industry. Without undue burden, Flipside could easily determine the meaning of the term.”); Hygrade Provision Co. v. Sherman, 266 U.S. 497, 502, 45 S.Ct. 141, 69 L.Ed. 402 (1925) (“[T]he term ‘kosher’ has a meaning well enough defined to enable one engaged in the trade to correctly apply it, at least as a general thing.”); Omaechevarria v. Idaho, 246 U.S. 343, 348, 38 S.Ct. 323, 62 L.Ed. 763 (1918) (“It is also urged that the Idaho statute, being a criminal one, is so indefinite in its terms as to violate the guaranty by the Fourteenth Amendment of the due process of law, since it fails to provide for the ascertainment of the boundaries of a ‘range’ or for determining what length of time is necessary to constitute a prior occupation a ‘usual’ one within the meaning of the act. Men familiar with range conditions and desirous of observing the law will have little difficulty in determining what is prohibited by it.”).
However, when we evaluate a provision, like the one at issue here, that regulates the conduct of the public at large and not a particular industry or subgroup, we do not impute specialized knowledge to the “person of ordinary intelligence” by whom we judge the statute’s vagueness. As the Supreme Court explained in Connally:
The precise point of differentiation in some instances is not easy of statement; but ... generally ... the decisions of the court, upholding statutes as sufficiently certain, rested upon the conclusion that they employed words or phrases having a technical or other special meaning, well enough known to enable those within their reach to correctly apply them, or a well-settled common law meaning, notwithstanding an element of degree in the definition as to which estimates might differ, or ... that, for reasons found to result either from the text of the statutes involved or the subjects with which they dealt, a standard of some sort was afforded.
269 U.S. at 391-92, 46 S.Ct. 126 (internal quotation marks and citations omitted); see Springfield Armory, Inc., 29 F.3d at 253 (holding city assault weapons ordinance unconstitutionally vague on its face because “[njothing in the ordinance provides sufficient information to enable a person of average intelligence to determine whether a weapon they wish to purchase has a design history of the sort which would bring it within this ordinance’s coverage. The record indicates that the average gun owner knows very little about how his gun operates or its *838design features. These vagueness problems are not difficult to remedy. The subject matter does allow for more exactness. It is,not a case in which greater specificity would interfere with practical administration. To the contrary, Columbus has many options for effectively pursuing its stated goals without running afoul of due process.”) (citations omitted).
Here, the term “cathinone” is sufficiently obscure that persons of ordinary intelligence reading the controlled substances schedules probably would not discern that possession of khat containing cathinone and/or cathine constitutes possession of a controlled substance. Persons seeking clarification of 21 C.F.R. § 1308.11(f) would be unaided by many mainstream dictionaries, as they contain no definitions for “cathinone” and make no reference to the chemical in their definitions of “khat.” See American Heritage Dictionary of the English Language 294, 961 (4th ed.2000) (including no definition for “cathinone” and defining “khat” as “1. An evergreen shrub CCatha edulis) native to tropical East Africa, having dark green opposite leaves that are chewed fresh for their stimulating effects. 2. A tealike beverage prepared from the leaves of this plant.”); Merriam-Webster’s Collegiate Dictionary 195, 685 (11th ed.2003) (providing no definition for “cathi-none” and defining “khat” as “a shrub (Catha edulis) of the staff-tree family cultivated in the Middle East and Africa for its leaves and buds that are the source of a habituating stimulant when chewed or used as a tea”); Oxford English Dictionary Online, at http://www.oed.com (containing no definition for “cathinone” and defining “kat” as “[a] shrub, Catha edulis, family Celastraceas, a native of Arabia, where it is extensively cultivated for its leaves, which have properties similar to those of tea and coffee; the narcotic drug obtained from the leaves of this plant.”).5
' We are hesitant to embrace the notion that statements linking cathinone and khat published in the Federal Register or the 1971 United Nations Convention on Psychotropic Substances would alone establish fair warning sufficient to sustain a criminal conviction in this case.6 Publication in the Federal Register of regulations which have the force of law does furnish constructive notice of the content of those regulations to those subject to them. See Yakus v. United States, 321 U.S. 414, 435, 64 S.Ct. 660, 88 L.Ed. 834 (1944) (citing 44 U.S.C. § 307, now codified as 44 U.S.C. § 1507). However, “Supplementary Information” accompanying an agency rule is separate from the text of the rule itself *839and is not codified in the Code of Federal Regulations. Hence, publication of the “Supplementary Information” in the Federal Register does not furnish notice sufficient to cure a vague criminal statute of its constitutional defect. See John Calvin Jef-fries, Jr., Legality, Vagueness, and the Construction of Penal Statutes, 71 Va. L.Rev. 189, 231 (Mar.1985) (asserting that “[t]he real source of notice is not the arcane pronouncements of the law reports but the customs of society and the sensibilities of people — what Holmes termed a sense of ‘common social duty.’... [I]t may well be that preoccupation with the concept of ‘lawyer’s notice’ has diverted our attention from instances of real unfairness.”) (quoting Nash, 229 U.S. at 377, 33 S.Ct. 780).
Despite these concerns, we are mindful of the fact that “[t]he classification of a federal statute as void for vagueness is a significant matter. The Supreme Court has held that every reasonable construction must be resorted to, in order to save a. statute from unconstitutionality.” Columbia Natural Res., 58 F.3d at 1105 (internal quotation marks and citations omitted); see Screws v. United States, 325 U.S. 91, 98, 65 S.Ct. 1031, 89 L.Ed. 1495 (1945) (“This Court has consistently favored that interpretation of legislation which supports its constitutionality.”).
Crimes arising out of the importation of controlled substances require proof that the defendant “knowingly or intentionally import[ed] ... a controlled substance ....” 21 U.S.C. § 960(a)(1). Thus, the concern that a person of ordinary intelligence could unwittingly expose himself or herself to criminal penalties due to the vagueness of the controlled substances schedules with respect to khat is overcome here because, as discussed in Part 11(B) below, conviction requires a showing of actual knowledge that khat contains a controlled substance. See Vill. of Hoffman Estates, 455 U.S at 499, 102 S.Ct. 1186 (“[T]he Court has recognized that a scien-ter requirement may mitigate a law’s vagueness, especially with respect to the adequacy of notice to the complainant that his conduct is proscribed.”); Boyce Motor Lines, Inc. v. United States, 342 U.S. 337, 342, 72 S.Ct. 329, 96 L.Ed. 367 (1952) (“The statute punishes only those who knowingly violate the Regulation. This requirement of the presence of culpable intent as a necessary element of the offense does much to destroy any force in the argument that application of the Regulation would be so unfair that it must be held invalid.”); Screws, 325 U.S. at 102-03, 65 S.Ct. 1031 (“[W]here the punishment imposed is only for an act knowingly done with the purpose of doing that which the statute prohibits, the accused cannot be said to suffer from lack of warning or knowledge that the act which he does is a violation of law .... [A] requirement of a specific intent ... saves the Act from any charge of unconstitutionality on the grounds of vagueness.”). Although the requirement of specific intent in this case mitigates any constitutional infirmity resulting from the vagueness of the controlled substances schedules, we caution against the drafting of criminal statutes, targeted at the general populace, that rely on obscure technical or scientific terms foreign to ordinary persons, lest we “sanction[] the practice of Caligula who ‘published the law, but it was written in a very small hand, and posted up in a corner, so that no one could make a copy of it.’ Suetonius, Lives of the Twelve Caesars, p. 278.” Screws, 325 U.S. at 96, 65 S.Ct. 1031.
B. Sufficiency of the Evidence
Caseer also asserts that his conviction cannot stand because the district *840court erred in denying his motion for judgment of acquittal and convicting him on the basis that he had sufficient notice and knowledge to satisfy the scienter requirement.7 Where, as here, the district court has conducted a bench trial, this court reviews the district court’s findings of fact for clear error and its conclusions of law de novo. See United States v. Al-Zubaidy, 283 F.3d 804, 808 (6th Cir.), cert. denied, 536 U.S. 948, 122 S.Ct. 2638, 153 L.Ed.2d 818 (2002); United States v. Atwell, 570 F.2d 650, 652 (6th Cir.1978). A district court has clearly erred when this court “is left with the definite and firm conviction that a mistake has been committed.” United States v. Jabara, 644 F.2d 574, 577 (6th Cir.1981) (internal quotation marks and, citations omitted).
When a defendant challenges his or her conviction after a bench trial on the basis of insufficiency of the evidence, we must determine “whether after reviewing the evidence in the light most favorable to the prosecution, any rational trier of fact could have found the essential elements of the crime beyond a reasonable doubt.” United States v. Bashaw, 982 F.2d 168, 171 (6th Cir.1992) (internal quotation marks and citation omitted); see also Al-Zubaidy, 283 F.3d at 808. All conflicts in testimony are resolved in the government’s favor, and every reasonable inference is drawn in favor of the government. Bashaw, 982 F.2d at 171. As the Fifth Circuit has accurately observed, “If the evidence, however, gives equal or nearly equal circumstantial support to a theory of guilt and a theory of innocence, we must reverse the conviction, as under these circumstances a reasonable jury must necessarily entertain a reasonable doubt.” United States v. Reveles, 190 F.3d 678, 686 (5th Cir.1999) (internal quotation marks and citations omitted).
In its analysis of the scienter requirement for the first count, conspiracy to import cathinone, the district court stated in summary fashion that:
Defendant Caseer testified that he requested Eldridge to bring back khat from Amsterdam. Defendant Caseer knowingly and voluntarily joined in the conspiracy ...
The Government has proven beyond a reasonable doubt that Defendant Caseer knowingly, intentionally and unlawfully conspired and agreed with Eldridge to import cathinone into the United States from Amsterdam, in violation of 21 U.S.C. § 846.
J.A. at 178 (D. Ct. Op. at 19). Likewise, in finding the intent element of the crime of aiding and abetting the importation of cathinone satisfied, the district court simply. stated that, “Defendant Caseer knowingly arranged , for the khat to be brought into the United States. Defendant Caseer had sufficient notice based on the above discussion that khat contains cathinone and/or cathine which are both scheduled substances.” J.A. at 179 (D. Ct. Op. at 20).
In ruling on Caseer’s fair-warning challenge to the controlled substances schedules, the district court also considered the extent of Caseer’s notice and knowledge. The district court first reviewed the May 1988 and January 1993 publications in the Federal Register relating to the listing of cathinone and cathine as controlled substances, and a notice of amendment to the U.S. Sentencing Guidelines providing for *841the treatment of khat as a marijuana equivalent. J.A. at 172-74 (D. Ct. Op. at 13-15). The district court next considered our decision in United States v. Hofstatter, 8 F.3d 316, 320 (6th Cir.1993), cert. denied, 510 U.S. 1131, 114 S.Ct. 1101, 127 L.Ed.2d 413 (1994), which noted in passing that khat contained cathinone, as well as state court cases from Maryland, Minnesota, and Connecticut treating khat as a controlled substance under state law. J.A. at 174-76 (D. Ct. Op. at 15-17). The district court then concluded as follows:
Because the terms “cathinone” and “khat” have been published in the Federal Register on more than one occasion, Defendant’s argument is without merit. The May 1988 Federal Regulations noted that “khat” is subject to Schedule IV, the same as “cathine.” The 1993 Federal Register notice indicating the addition of cathinone as a scheduled drug made reference to “khat” — that cathinone is found in khat. The 1993 Federal Register indicated that as far back as 1971, the international community has recognized the effect of “cathinone” and “khat” as evidenced by the 1971 United Nations Convention on Psychotropic Substances. Subsequent publications in the Federal Register have since referred to “khat” including the Sentencing Guidelines in 1995. “Khat” has been an unapproved for importation by the FDA since the early 1980’s and the FDA issued publications in the Federal Register regarding “khat” in 1995 and 1996. Additionally, the State cases addressing the notice issue of a State prosecution for “khat” and “cathinone” have found that the defendants had adequate notice and fair warning regarding the possession of khat. All these references to “khat” in the Federal Register, the United Nations Convention, the State cases cited above and the Sixth Circuit noting that “khat” contains “cathinone,” serve sufficient notice that “khat,” if it contains cathinone, is a Scheduled I drug and a Scheduled IV drug if it contains cathine. Defendant Caseer was aware of the stimulant effect of khat. He testified that khat is a stimulant and gives energy like tea and coffee. Even though he testified that he did not know that khat or cathinone was illegal, he was aware that khat could be seized or confiscated at Customs. Defendant Ca-seer had sufficient notice and had knowledge that khat, if it contains cathinone and/or cathine, is a scheduled drug. Defendant Caseer also had sufficient notice and knowledge that khat is a stimulant and that the importation of khat is prohibited and illegal. Defendant Caseer’s Motion for Judgment of Acquittal must . be denied.
J.A. at 176-77 (D. Ct. Op. at 17-18).
As we concluded above in our analysis of Caseer’s fair-warning claim, the criminal provisions at issue here are saved from potential unconstitutionality because 21 U.S.C. § 960 establishes as an element of the offenses that the accused knowingly or intentionally imported a controlled substance. Thus, to convict Caseer properly of the charged offenses, the district court would need to have found beyond a reasonable doubt that Caseer actually knew that khat contained a controlled substance.8 *842See Hussein, 351 F.3d at 17 (upholding jury instruction that, in order to find that the defendant knowingly possessed cathi-non'e, “the government must prove beyond a reasonable doubt that [the defendant] [1] knew that'the substance he possessed contained cathinone, or [2] knew that the substance he possessed contained a controlled substance. A controlled substance is a drug or other substance regulated under federal drug abuse law.”) (second and third alterations and emphasis added in Hussein); United States v. Restrepo-Granda, 575 F.2d 524, 527 (5th Cir.), cert. denied, 439 U.S. 935, 99 S.Ct. 331, 58 L.Ed.2d 332 (1978) (“Although knowledge that the substance imported is a particular narcotic need not be proven, 21 U.S.C. 952(a) is a ‘specific intent’ statute and requires knowledge that such substance is a controlled;substance.”) (citations omitted); see also United States v. Jones, 81 Fed.Appx. 45, 48 (6th Cir.2003), cert. denied, 541 U.S. 954, 124 S.Ct. 1699, 158 L.Ed.2d 388 (2004) (“Pursuant to 21 U.S.C. § 841(a)(1), it is unlawful for any person to knowingly or intentionally manufacture, distribute, or dispense, or possess with intent to manufacture, distribute, or dispense, a controlled substance. To convict a defendant under § 841(a)(1), the Government must prove beyond a reasonable doubt that: (1) the defendant possessed the controlled substance described in the indictment; (2) the defendant knew the substance was a controlled substance; and (3) the defendant intended to distribute the controlled substance.”) (internal quotation marks and citations omitted); United States v. Decker, 19 F.3d 287, 288, 290 (6th Cir.1994). Keeping in mind that the government must prove beyond a reasonable doubt that Caseer knew khat contained a controlled substance, we now turn to the facts identified by the district court as supporting its finding of scienter, considering whether the district court clearly erred in making any individual fact findings and whether the evidence taken as a whole is sufficient that a reasonable trial judge could conclude beyond a reasonable doubt that Caseer had the requisite intent for conviction.
First, the district court points to the 1971 United Nations Convention on Psychotropic Substances and several Federal Register publications that explain that khat contains cathine and cathinone, that establish marijuana equivalency for sentencing of khat-related crimes, and that indicate that khat may be subject to FDA regulation. Although Caseer might be charged with constructive knowledge of the contents of these documents, the mere existence of these documents does not speak to whether Caseer had actual knowledge of their contents. The district court made no finding, and the record furnishes no evidence, that Caseer read or was otherwise familiar with any of these publications. Thus, the existence of the United Nations and Federal Register publications provides no support for a finding of scien-ter in this case.
Second, the district court cites this court’s decision in Hofstatter and several state prosecutions for khat-related offenses as evidence that Caseer knew khat was a controlled substance. In Hofstat-ter, we affirmed the convictions of two defendants charged with possessing and conspiring to possess listed precursor chemicals with the intent to manufacture controlled substance analogues. We noted in passing that during a search of one *843of the defendants’ automobiles, DEA agents:
found two bags containing personal papers, notebooks, and envelopes in the name of [the codefendant]. The documents described “khat” (an East African plant containing cathinone) and methy-laminorex .... Formulae for the manufacture of methylcathinone were found in the car, as was a Federal Register notice indicating that methylaminorex was to be scheduled as a controlled substance by the DEA.
8 F.3d at 320. In the absence of proof that Caseer read or was otherwise aware of our decision in Hofstatter, concluding that this single reference in Hofstatter to khat furnished the actual notice to Caseer required for conviction in the present case would be clear error. Moreover, the state cases referenced by the district court, Connecticut v. Gurreh, 60 Conn.App. 166, 758 A.2d 877 (2000); Warsame v. Maryland, 338 Md. 513, 659 A.2d 1271 (1995); and Minnesota v. Ali, 613 N.W.2d 796 (Minn.Ct.App.2000), all pertain to state, not federal, controlled substances statutes, and there is no evidence to suggest that Caseer had ever been subject to the laws of these three states. Hence, it cannot be inferred from the existence of these four cases that Caseer knew that khat contains controlled substances regulated by the federal government.
Third, the district court found that Ca-seer was “aware of the stimulant effect of khat” based on Caseer’s trial testimony9 that “khat is a stimulant and gives energy like tea or coffee.” J.A. at 177 (D. Ct. Op. at 18). Although actual knowledge that a substance is controlled might in some cases be inferred from the physical effects caused by the substance, in this case the stimulant- effect of khat is too mild to permit a reasonable inference that Caseer knew that khat contained a controlled substance. The district court’s opinion indicates that Caseer knew only that khat had a mild stimulant effect and indeed seems to suggest that chewing khat is the. Somali equivalent of drinking coffee or tea in the United States. The seeming ubiquity of coffee houses in the United States attests to the fact that consuming products with stimulating effects is common custom. in the United States, and the average American coffee drinker most likely does not pause to consider, while drinking his or her morning “cup of Joe” whether he or she may be subject to criminal sanct0ion for possession of a controlled substance. , See Lambert v. California, 355 U.S. 225, 229-30, 78 S.Ct. 240, 2 L.Ed.2d 228 (1957) (reversing conviction for failure to comply with felon-registration ordinance, explaining that, “As Holmes vyrote in The Common Law, ‘A law which, punished conduct which would not be blameworthy in the , average member of the community would .be too severe for that community to bear.’ Its severity lies in the absence of an opportunity either to avoid the consequences of the law or to defend any prosecution brought under it. Where a person did not know of thé duty to register and where there was no proof of the probability of such knowledge, he may not be convicted consistently with due process. Were it otherwise, the evil woüld be as great as it is when the law is written in print too fine *844to read or in a language foreign to the community.”)- Thus, Caseer’s awareness of the mild stimulant effect of khat provides little support for the conclusion that Caseer actually knew that the khat he was importing was a controlled substance.
Finally, the district court found that, although Caseer “testified that he did not know that khat or cathinone was illegal, he was aware that khat could be seized or confiscated at Customs.” J.A. at 177 (D. Ct. Op. at 18). Not all items that may be seized by the U.S. Customs Service, however, are classified as controlled substances pursuant to 21 U.S.C. § 812 and 21 C.F.R. § 1308.11. Thus, while the district court could reasonably infer from Caseer’s testimony that Caseer knew importation of khat violated U.S. customs laws, it is less reasonable to infer that Caseer knew he would be violating U.S. drug laws by importing a controlled substance.10
In sum, the evidence cited by the district court in its determination of whether Caseer had the requisite scienter for conviction lends, at best, only tenuous support for the conclusion that Caseer knew that he was participating in the importation of a controlled substance. Even drawing all inferences in the light most favorable to the government, a rational trier of fact would have reasonable doubt that Caseer knew that khat was a controlled substance. Thus, Caseer’s conviction cannot stand.
III. CONCLUSION
For the reasons set forth above, we conclude that, although the criminal provisions at issue are not unconstitutional for failure to furnish fair warning, we must REVERSE the judgment of conviction because of the insufficiency of the evidence and REMAND the case to the district court for further proceedings consistent with this decision.
. At the time of these events, Caseer was awaiting approval of his application for permanent residency status. Caseer admitted at trial that he had traveled to Germany a few weeks prior to these events, but that, unlike the Netherlands, Germany did not require a visa.
. Douglas Panning, an agent with the United States Customs Service, testified that the U.S. Customs Service’s practice at that time was to levy $500.00 fines for small amounts of khat intended for personal use if federal or local authorities decided not to prosecute.
. There appear to be several inconsistencies amongst the indictment, the district court opinion, and the district court’s judgment as to the specific U.S.Code provisions Caseer is accused of violating.
With respect to the first count, the indictment lists the charge as "Conspiracy to Distribute Cathinone” in violation of 21 U.S.C. § 846, but the text of the indictment refers to conspiracy to import cathinone, in violation of 21 U.S.C. §§ 952, 963. Joint Appendix ("J.A.”) at 7 (Indictment). We conclude that the district court correctly treated the charge as conspiracy to import cathinone in violation of 21 U.S.C. §§ 952, 963. J.A. at 160 (D.Ct. Op. n. 1); J.A. at 181 (Judgment).
With, respect to the second count, the indictment's subheading lists the offense as "21 U.S.C. § 841(a)(1) — Importation of Cathinone; 18 U.S.C. § 2 — Aiding and Abetting.” J.A. at 8 (Indictment). However, § 841(a)(1) pertains to the manufacture, distribution, and dispensing of controlled substances, not their importation. Based on the references to importation in the text of the indictment and its citation to 21 U.S.C. § 952, which governs importation, the district court correctly treated the charge as arising under § 952. J.A. at 160 (D.Ct.Op. n. 2); J.A. at 181 (Judgment).
. As with the Federal Register document that includes the text of the final rule listing cathi-none as a controlled substance, the portion'of the Federal Register publication listing cath-ine as a controlled substance notes the relationship between lchat and cathine only in the Supplementary Information section and not in the text of the rule included in the Code of Federal Regulations. Compare Schedules of Controlled Substances; Temporary Placement of Cathine ((+) — norpseudophedrine), Fen-camfamin, Fenproporex and Mefenorex Into Schedule IV, 53 Fed.Reg. 17,459, 17,460 (May 17, 1988) (noting relationship between khat and cathine in Supplementary Information section), with 21 C.F.R. § 1308.14(e)(1) (listing cathine as a Schedule IV controlled substance but including no reference to khat).
. We also note that the failure to include a reference to the khat shrub in the controlled substances schedule is not, as the government contends, akin to omitting street names or slang terms. In United States v. Levy, we rejected a challenge to the use of the term “cocaine base” in lieu of "crack cocaine,” stating that, “The fact that a type of contraband may have various nicknames on the street does not render a statute punishing possession of that contraband invalid simply because it fails to list all of the then-current nicknames.” 904 F.2d 1026, 1033 n. 1 (6th Cir.1990), cert. denied, 498 U.S. 1091, 111 S.Ct. 974, 112 L.Ed.2d 1060 (1991). Here, in contrast, referring to the botanical source of cathinone as “khat” is not a passing fad that would require repeated amendment of the controlled substances schedules, but rather is the commonly accepted method of referencing the plant Catha edulis.
. We also reject the contention that the U.S. Sentencing Guidelines' establishment of marijuana equivalency for khat-related offenses furnished Caseer sufficient fair warning of the illegality of khat. See United States v. Smith, 73 F.3d 1414, 1417 (6th Cir.1996) (rejecting vagueness challenge to Sentencing Guidelines provision, stating that, "The Sentencing Guidelines do not establish the illegality of any conduct. Rather, they are directives to judges and not citizens.”) (internal quotation marks and citation omitted).
. Because we conclude that the evidence presented at trial is insufficient to sustain Ca-seer's conviction, we need not address whether, based on the evidence presented in the government’s case-in-chief, the district court erred in denying Caseer’s Rule 29 motion for judgment of acquittal.
. This is not to suggest that in all Controlled Substances Act prosecutions the government must prove beyond a reasonable doubt that the defendant had actual knowledge that the substance at issue is controlled. For substances such as cocaine that are controlled per se under the controlled substances schedules and for which there are no due process fair-warning concerns, constructive knowledge inferred from the listing of the substance in the controlled substances schedules may suffice. However, when a targeted item, such as khat, is not itself listed in the controlled substances schedules, due process requires *842■that the'government prove beyond a reasonable doubt that the defendant had actual ■ knowledge that the targeted item contained a controlled substance regulated under federal drug abuse laws. See United States v. Hussein, 351 F.3d 9, 17-19 (1st Cir.2003).
. We note that the district court erred to the extent.it relied on Caseer's testimony in ruling on his motion for judgment of acquittal. Because the district court reserved ruling on the motion at the close of the government's casein-chief, the district court should have considered only the evidence put on by the government and not any evidence presented by Ca-seer in his own defense. See Fed.R.Crim.P. 29(b) (providing that when a court has reserved ruling on a motion for. judgment of acquittal, the court "must decide the motion on the basis of the evidence at the time the ruling was reserved”).
. The government also contends that it is reasonable to infer from Caseer’s behavior in arranging for the importation of khat and his subsequent conduct during the government’s investigation that Caseer knew khat was a controlled substance. The district court did not make any findings regarding Caseer's state of mind based on such behavior, and arguably such conduct is consistent with that of a recent immigrant concerned with violating U.S. customs laws. Any inference from this evidence that Caseer knew he would be importing a controlled substance, and not simply an agricultural product regulated by customs laws, would be weak at best and insufficient to permit a rational trier of fact to conclude beyond a reasonable doubt that Caseer had actual knowledge that the khat he imported was a controlled substance. See Hussein, 351 F.3d at 20-21 (finding "very close” the question of whether sufficient evidence of scienter had been presented to sustain conviction, notwithstanding that the defendant: (1) "was a knowledgeable individual; he was not a recent immigrant, but a successful businessman who had been in the United States for a number of years;” (2) knew that khat was a stimulant; (3) had made prior trips to pick up khat for a local distributor; and (4) knew that the methods for sending and receiving packages, including mislabeling, use of fake addresses, and recruitment of multiple couriers, were "elaborately contrived to avoid detection”).