MPG: Gateway

Welcome to MASSACHUSETTS CRIMINAL LAW: A PROSECUTOR'S GUIDE Online.

On this site, you will find the full text of the 44th edition of the Prosecutor's Guide. The Guide presents a timely and comprehensive analysis of Massachusetts criminal law and its practice in the courts of the Commonwealth and cites to over 7,000 Massachusetts criminal decisions by the Supreme Judicial and Appeals Courts. It is fully updated each fall and during the year as new developments in the law warrant. Please consult our What's New page for the most recent changes.

The text also cites and discusses significant criminal law cases decided by the Supreme Court, the federal Courts of Appeals, and state appellate courts from around the country. The principal focus, however, is on Massachusetts criminal law and its practice in the courts of the Commonwealth.

Access to the Guide is by annual subscription. If you are not yet a subscriber, please take the tour of a sample chapter from the Guide.

Please Note: If you are an employee of the Massachusetts Trial Court or an Assistant District Attorney, you have unlimited access to the Prosecutor's Guide web site thanks to licenses purchased on your behalf by the Massachusetts Trial Court Law Library and the Massachusetts District Attorneys Association, respectively. Please contact your office law library for access instructions. In the case of ADAs, access to the Guide is through your account on the New York Prosecutors Training Institute website.

Also law students at the following institutions have access through your school Law Library: Harvard, Suffolk, Boston College, Northeastern, Western New England School of Law, New England Law | Boston, Boston University, and the University of Massachusetts.

Please note:
9/8/25: "Criminal Trespass" and "Motor Vehicle Offenses" have been revised, the latter to include important new cases on the already relaxed meaning of "operating" a motor vehicle for purposes of an OUI conviction as well as an important new case on the nonconsensual extraction of blood samples, Commonwealth v. Zucchino, 493 Mass. 747 (2024), which trims back earlier cases which appeared to misread the aggravated drunk driving statutes. 9/3/25: "Threshold Inquiries" has been revised to note new cases on topics such as the community caretaking doctrine and racial profiling, including the important new case of Commonwealth v. Diaz, 496 Mass. 210 (2025). 8/25/25: "Search and Seizure" has been updated to note new cases discussing wiretapping, inmate privacy, the GPS monitoring of detainees, and the attenuation doctrine, among other topics. 8/11/25: The chapter on "Multiple Defendants" and "Juvenile Justice" has been revised to note, among others, new cases discussing the joint venture doctrine, attorney conflicts of interest, and the sentencing of juvenile offenders. Please see What's New for further details.

Please note:

9/8/25: "Criminal Trespass" and "Motor Vehicle Offenses" have been revised, the latter to include important new cases on the already relaxed meaning of "operating" a motor vehicle for purposes of an OUI conviction as well as an important new case on the nonconsensual extraction of blood samples, Commonwealth v. Zucchino, 493 Mass. 747 (2024), which trims back earlier cases which appeared to misread the aggravated drunk driving statutes.

9/3/25: "Threshold Inquiries" has been revised to note new cases on topics such as the community caretaking doctrine and racial profiling, including the important new case of Commonwealth v. Diaz, 496 Mass. 210 (2025).

8/25/25: "Search and Seizure" has been updated to note new cases discussing wiretapping, inmate privacy, the GPS monitoring of detainees, and the attenuation doctrine, among other topics.

8/11/25: The chapter on "Multiple Defendants" and "Juvenile Justice" has been revised to note, among others, new cases discussing the joint venture doctrine, attorney conflicts of interest, and the sentencing of juvenile offenders.

Please see What's New for further details.