(3g) Possession. No person may possess or attempt to possess a controlled substance or a controlled substance analog unless the person obtains the substance or the analog directly from, or pursuant to a valid prescription or order of, a practitioner who is acting in the course of his or her professional practice, or unless the person is otherwise authorized by this chapter to possess the substance or the analog. Any person who violates this subsection is subject to the following penalties:
(am) Schedule I and II narcotic drugs. If a person possesses or attempts to possess a controlled substance included in schedule I or II which is a narcotic drug, or a controlled substance analog of a controlled substance included in schedule I or II which is a narcotic drug, the person is guilty of a Class I felony.
(b) Other drugs generally. Except as provided in pars. (c) to (g), if the person possesses or attempts to possess a controlled substance or controlled substance analog, other than a controlled substance included in schedule I or II that is a narcotic drug or a controlled substance analog of a controlled substance included in schedule I or II that is a narcotic drug, the person is guilty of a misdemeanor, punishable under s. 939.61.
(c) Cocaine and cocaine base. If a person possesses or attempts to possess cocaine or cocaine base, or a controlled substance analog of cocaine or cocaine base, the person shall be fined not more than $5,000 and may be imprisoned for not more than one year in the county jail upon a first conviction and is guilty of a Class I felony for a 2nd or subsequent offense. For purposes of this paragraph, an offense is considered a 2nd or subsequent offense if, prior to the offender’s conviction of the offense, the offender has at any time been convicted of any felony or misdemeanor under this chapter or under any statute of the United States or of any state relating to controlled substances, controlled substance analogs, narcotic drugs, marijuana, or depressant, stimulant, or hallucinogenic drugs.
(d) Certain hallucinogenic and stimulant drugs. If a person possesses or attempts to possess lysergic acid diethylamide, phencyclidine, amphetamine, 3,4-methylenedioxymethamphetamine, methcathinone, cathinone, N-benzylpiperazine, a substance specified in s. 961.14 (4) (a) to (h), (m) to (q), (sm), (u) to (xb), or (7) (L), psilocin, or psilocybin, or a controlled substance analog of lysergic acid diethylamide, phencyclidine, amphetamine, 3,4-methylenedioxymethamphetamine, methcathinone, cathinone, N-benzylpiperazine, a substance specified in s. 961.14 (4) (a) to (h), (m) to (q), (sm), (u) to (xb), or (7) (L), psilocin, or psilocybin, the person may be fined not more than $5,000 or imprisoned for not more than one year in the county jail or both upon a first conviction and is guilty of a Class I felony for a 2nd or subsequent offense. For purposes of this paragraph, an offense is considered a 2nd or subsequent offense if, prior to the offender’s conviction of the offense, the offender has at any time been convicted of any felony or misdemeanor under this chapter or under any statute of the United States or of any state relating to controlled substances, controlled substance analogs, narcotic drugs, marijuana, or depressant, stimulant, or hallucinogenic drugs.
(e) Tetrahydrocannabinols. If a person possesses or attempts to possess tetrahydrocannabinols included under s. 961.14 (4) (t), or a controlled substance analog of tetrahydrocannabinols, the person may be fined not more than $1,000 or imprisoned for not more than 6 months or both upon a first conviction and is guilty of a Class I felony for a 2nd or subsequent offense. For purposes of this paragraph, an offense is considered a 2nd or subsequent offense if, prior to the offender’s conviction of the offense, the offender has at any time been convicted of any felony or misdemeanor under this chapter or under any statute of the United States or of any state relating to controlled substances, controlled substance analogs, narcotic drugs, marijuana, or depressant, stimulant, or hallucinogenic drugs.
(em) Synthetic cannabinoids. If a person possesses or attempts to possess a controlled substance specified in s. 961.14 (4) (tb), or a controlled substance analog of a controlled substance specified in s. 961.14 (4) (tb), the person may be fined not more than $1,000 or imprisoned for not more than 6 months or both upon a first conviction and is guilty of a Class I felony for a 2nd or subsequent offense. For purposes of this paragraph, an offense is considered a 2nd or subsequent offense if, prior to the offender’s conviction of the offense, the offender has at any time been convicted of any felony or misdemeanor under this chapter or under any statute of the United States or of any state relating to controlled substances, controlled substance analogs, narcotic drugs, marijuana, or depressant, stimulant, or hallucinogenic drugs.
(f) Gamma-hydroxybutyric acid, gamma-butyrolactone, 1,4-butanediol, ketamine, or flunitrazepam. If a person possesses or attempts to possess gamma-hydroxybutyric acid, gamma-butyrolactone, 1,4-butanediol, ketamine or flunitrazepam, the person is guilty of a Class H felony.
(g) Methamphetamine. If a person possesses or attempts to possess methamphetamine or a controlled substance analog of methamphetamine, the person is guilty of a Class I felony.
http://docs.legis.wisconsin.gov/statutes/statutes/961/IV/41/3g
