Go to the source: in the last six years, many SJC and Appeals Court briefs have been made available on the State court website, shortly before they are argued. Links to briefs are found on a case's docket page, just above docket entries. The Trial Court Law Libraries are working to set up links to briefs directly from individual cases on our Massachusetts Cases page.
Some Trial Court Law Libraries have an online subscription to Westlaw's Briefs database. Coverage is selective and starts in 1999. The next option is microfiche. There are four libraries in the Mass Trial Court System that have Massachusetts SJC Records and Briefs on microfiche, and five that have Massachusetts Appeals Court Records and Briefs on microfiche.
To obtain a brief or other legal material, contact your local law library, or put in a request through Document Delivery.
See our page on Massachusetts Rules of Appellate Procedure for rules 16 to 20 on briefs.