Commonwealth v. Mattis

Sheldon Mattis was tried as a joint-venturer for a shooting when he was 18 years old and sentenced to mandatory life without parole. The MacArthur Justice Center, alongside The Sentencing Project and Juvenile Law Center, filed an amicus brief highlighting that the Massachusetts Supreme Judicial Court should extend the prior ruling to all youth over 18 in alignment with existing science and based on an independent reading of the Massachusetts Declaration of Rights.  

Mr. Mattis appealed his mandatory life without parole sentence, and the Massachusetts Supreme Judicial Court remanded the case to the state’s Superior Court to determine whether, in the face of emerging scientific research regarding adolescent brain development after 17 years old, sentences of life-without-parole for individuals ages 18 to 20 violated the state’s Eighth Amendment.  

Following the evidentiary hearing, the Superior Court concluded that mandatory life without parole sentences for this class of individuals does indeed constitute “cruel or unusual punishment” in violation of the state constitution. 

The case returned to the Supreme Judicial Court, which called for amicus briefs concerning whether a prior ruling that “life-without-parole sentences for youth under 18 years old violate the State’s constitution” should be extended to also include individuals ages 18-20. 

The MacArthur Justice Center (MJC), in collaboration with The Sentencing Project and Juvenile Law Center, filed an amicus brief, arguing that the justifications for life-without-parole sentences for older adolescents fail in the same way they fail for youth under 18, and neither science nor society considers 18 to be the age at which a child achieves full maturity, the Supreme Judicial Court should broaden its ruling in Diatchenko I to hold that article 26 bars life-without-parole sentences for youth over 18.