Mass. Gen. Laws ch. 94C § 34
No person knowingly or intentionally shall possess a controlled substance unless such substance was obtained directly, or pursuant to a valid prescription or order, from a practitioner while acting in the course of his professional practice, or except as otherwise authorized by the provisions of this chapter. Except as provided in Section 32L of this Chapter or as hereinafter provided, any person who violates this section shall be punished by imprisonment for not more than one year or by a fine of not more than one thousand dollars, or by both such fine and imprisonment. Any person who violates this section by possessing heroin shall for the first offense be punished by imprisonment in a house of correction for not more than two years or by a fine of not more than two thousand dollars, or both, and for a second or subsequent offense shall be punished by imprisonment in the state prison for not less than two and one-half years nor more than five years or by a fine of not more than five thousand dollars and imprisonment in a jail or house of correction for not more than two and one-half years. Any person who violates this section by possession of more than one ounce of marihuana or a controlled substance in Class E of section thirty-one shall be punished by imprisonment in a house of correction for not more than six months or a fine of five hundred dollars, or both. Except for an offense involving a controlled substance in Class E of section thirty-one, whoever violates the provisions of this section after one or more convictions of a violation of this section or of a felony under any other provisions of this chapter, or of a corresponding provision of earlier law relating to the sale or manufacture of a narcotic drug as defined in said earlier law, shall be punished by imprisonment in a house of correction for not more than two years or by a fine of not more than two thousand dollars, or both.
If any person who is charged with a violation of this section has not previously been convicted of a violation of any provision of this chapter or other provision of prior law relative to narcotic drugs or harmful drugs as defined in said prior law, or of a felony under the laws of any state or of the United States relating to such drugs, has had his case continued without a finding to a certain date, or has been convicted and placed on probation, and if, during the period of said continuance or of said probation, such person does not violate any of the conditions of said continuance or said probation, then upon the expiration of such period the court may dismiss the proceedings against him, and may order sealed all official records relating to his arrest, indictment, conviction, probation, continuance or discharge pursuant to this section; provided, however, that departmental records which are not public records, maintained by police and other law enforcement agencies, shall not be sealed; and provided further, that such a record shall be maintained in a separate file by the department of probation solely for the purpose of use by the courts in determining whether or not in subsequent proceedings such person qualifies under this section. The record maintained by the department of probation shall contain only identifying information concerning the person and a statement that he has had his record sealed pursuant to the provisions of this section. Any conviction, the record of which has been sealed under this section, shall not be deemed a conviction for purposes of any disqualification or for any other purpose. No person as to whom such sealing has been ordered shall be held thereafter under any provision of any law to be guilty of perjury or otherwise giving a false statement by reason of his failure to recite or acknowledge such arrest, indictment, conviction, dismissal, continuance, sealing, or any other related court proceeding, in response to any inquiry made of him for any purpose.
Notwithstanding any other penalty provision of this section, any person who is convicted for the first time under this section for the possession of marihuana or a controlled substance in Class E and who has not previously been convicted of any offense pursuant to the provisions of this chapter, or any provision of prior law relating to narcotic drugs or harmful drugs as defined in said prior law shall be placed on probation unless such person does not consent thereto, or unless the court files a written memorandum stating the reasons for not so doing. Upon successful completion of said probation, the case shall be dismissed and records shall be sealed.
It shall be a prima facie defense to a charge of possession of marihuana under this section that the defendant is a patient certified to participate in a therapeutic research program described in chapter ninety-four D, and possessed the marihuana for personal use pursuant to such program.
Notwithstanding any general or special law to the contrary, a laboratory may possess, store, analyze, process and test medical marijuana and medical marijuana-infused products; provided, however, that such laboratory shall do so in accordance with the department's regulations and written guidelines governing procedures for quality control and testing of products for potential contaminants.
Mass. Gen. Laws ch. 94C, § 34