Madriz-Alvarado v. Ashcroft, 383 F.3d 321 (5th Cir. Aug. 27, 2004) (petition for review denied, despite contention that deferred adjudication for drug possession did not constitute conviction for immigration purposes by analogy to the Federal First Offender Act).
http://caselaw.lp.findlaw.com/data2/circs/5th/0320126p.pdf

There is some risk that since the simulated controlled substances is sold "as" a controlled substance, a court would rule the state law prohibiting it would be a law "related to" a controlled substance.  Such a violation should not be an aggravated felony, however, since the federal counterfeit controlled substances law does not cover sale of flour pretending it is a controlled substance.  See 21 U.S.C. 802(7) ("counterfeit controlled substance" must be a "controlled substance" pretending to be manufactured by someone other than the actual manufacturer), 841(a)(2) (sale, etc.

Immigration counsel can argue that a person convicted of aiding and abetting the commission of a deportable offense is not deportable unless the definition of aiding and abetting, under the law of the jurisdiction of conviction, is coextensive with the federal definition of aiding and abetting. For example, in California, a person can be convicted of aiding and abetting on the basis of mere encouragement, even if no actual assistance is provided. This form of aiding a theft offense has been held insufficient to constitute a theft offense aggravated felony. United States v.

Urena-Ramirez v. Ashcroft, 341 F.3d 51 (1st Cir. August 22, 2003) (federal conviction under the Travel Act for promoting an unlawful activity involving controlled substances constitutes a controlled substance conviction, rendering noncitizen ineligible for adjustment of status).
http://laws.lp.findlaw.com/1st/022343.html

In Matter of Seda, 17 I. & N. Dec. 550 (BIA 1989), overruled by Matter of Ozkok, 19 I. & N. Dec. 546 (1988) on other grounds, the BIA said that a judicial admission that did not lead to a conviction would not be a ground of inadmissibility as an admission, but it could still be considered as an unfavorable factor in discretionary determinations.  See 8 C.F.R. 316.10(B)(2) (i)&(iv) (concerning admissions not constituting a bar under the petty offense exception), and (3) concerning discretion and "extenuating circumstances."

Matter of CYC, 3 I. & N. Dec. 623 (BIA 1949) (where there has been a judicial adjudication of the criminal charge before the court, resulting in the dismissal of the proceedings, the noncitizen should not be held bound by an independent admission of the commission of the crime charged unless the criminal court's action is based on purely technical grounds, such as the running of the statute of limitations or an acquittal obtained on the basis of perjured testimony)
In Matter of CYC, 3 I. & N. Dec. 623, 629, 1949 WL 6509 (BIA 1949), the BIA held:

An adjudication of delinquency is not a conviction for immigration purposes. Matter of Devison, 22 I. & N. Dec. 1362 (BIA 2000). However, a noncitizen can be inadmissible from the United States if s/he admits the essential elements of a crime involving moral turpitude or a controlled substance offense. In order for a noncitizens statements to constitute a valid admission: (1) the conduct must be for something that is a crime, (2) the government must provide a plain language description of the crime, and (3) the admission must be voluntary.

Javier Ramon Lopez Molina v. Ashcroft, 368 F.3d 1206 (9th Cir. 2004); Oscar Rojas-Garcia v. Ashcroft, 339 F.3d 814 (9th Cir. 2003); Luis Alarcon-Serrano v. INS, 220 F.3d 1116 (9th Cir. 2000).

Lopez-Molina v. Ashcroft, 368 F.3d 1206 (9th Cir. June 2, 2004) (suspicious meetings between noncitizen and other suspects, several of whom were arrested with several thousand dollars in cash, noncitizen's attempt to escape when police stopped the vehicle he was driving, and discovery of 147 pounds of marijuana in the trunk, plus a guilty plea to failure to disclose to authorities his knowledge of a conspiracy to distribute marijuana, not rebutted by the noncitizen, constituted sufficient evidence to support reason to believe he was inadmissible as illicit trafficker).

Alarcon-Serrano v. INS, 220 F.3d 1116, 1119 (9th Cir. 2000) (immigration official must have "reasonable, substantial, and probative evidence" that noncitizen knew he was participating in illicit drug trafficking to support finding of inadmissibility under INA 212(a)(2)(C)(i), 8 U.S.C. 1182(a)(2)(C)(i)), citing Hamid v. INS, 538 F.2d 1389, 1390-91 (9th Cir. 1976); Lopez-Molina v. Ashcroft, 368 F.3d 1206 (9th Cir. June 2, 2004).