BOSTON – Women do not open themselves to criminal charges by giving birth without medical assistance, the highest court in Massachusetts said Friday as it ruled in the case of a Milford woman who gave birth to a nearly full-term baby whose body was later found in the trash.

The Supreme Judicial Court said the state has adequate criminal laws prohibiting murder, most late-term abortions, and the neglect and abuse of children to protect viable fetuses and living children “without the need to subject all women undergoing unassisted childbirth to possible criminal liability.”

“Imposing a broad and ill-defined duty on all women to summon medical intervention during childbirth would trench on their ‘protected liberty interest in refusing medical treatment,”‘ Justice Barbara Lenk wrote for the court in the unanimous opinion.

The ruling reversed the involuntary manslaughter conviction of Allissa Pugh. Because prosecutors had not proved that her baby was born alive or that calling for medical help would have saved his life, they lacked evidence that Pugh’s failure to call for help was the cause of the baby’s death, the court ruled.

The infant’s body was found in January 2007 as haulers were collecting trash in Pugh’s neighborhood.

Pugh told police she believed she was only three months pregnant and possibly having a miscarriage when she gave birth at home. She said that after her water broke, she felt the baby’s foot first, realized it was in a breech position and thought she should hasten the baby’s birth. She said she pushed about 10 times and pulled on the baby to speed up the delivery. The infant was delivered a few minutes later, but was blue and unresponsive, she said. She later put the baby’s body in the trash.