When can a child ride in front seat in Mass?

When can a child ride in front seat in Mass?
There are no "front seat" laws in Massachusetts.

In April, 2008, Governor Patrick signed Bill 2018 - The BoosterSeat Bill, into law. The law went into effect on July 10, 2008.

Basically, the law states:
"no child under the age of eight and measuring less than
fifty-seven inches shall ride as a passenger in a motor vehicle onany
way unless such child is properly fastened and secured, accordingto
the manufacturers' instructions, by a child passenger restraint".
The new law also states that children ages eight to twelve arerequired
to wear a safety belt when traveling in a motor vehicle.

However:
Industry best practices for front seats in vehicles recommends:
Children 12 and younger should never sit in the front seat. Thesafest seating position is in the back seat, away from air bags, ifpossible.

For more information, please refer to the related link.